THE  UNIVERSITY 

OF  ILLINOIS 

LIBRARY 


1 


NATURAL  HISTORY  SURVEY 

ILL 
v.3cop.4 


ILLINOIS  BIOLOGICAL 
MONOGRAPHS 


Vol.111  January.  1917  No.  3 


Editorial  Committee 


Stephen  Alfred  Forbes  William  Trelease 

Henry  Baldwin  Ward 


Published  under  the 

Auspices  of  the  Graduate  School  Bt 

THE  University  of  Illinois 


Copyright,  191 7 

By  the  University  of  Illinois 

Distributed  May  5,  1917 


STUDIES  ON  NORTH 

AMERICAN  POLYSTOMIDAE, 

ASPIDOGASTRIDAE,  AND 

PARAMPHISTOMIDAE 


WITH  ELEVEN  PLATES 


BT 

HORACE  WESLEY  STUNKARD 


Ooatributlona  from  the 
Zoological  Laboratory  of  the  ITniversity  of  flUnols  under 
the  direction  of  Uenrjr  B.  Ward,  No.  84 


THESIS 

Submitted  in  Partial  Fulfillment  of  the  Requirements  for  the 

Degree   of   Doctor  of   Philosophy  in  Zoology 

in  the  Graduate  School  of  the 

University  of  Illinois 

1916 


TABLE  OF  CONTENTS 


PAGE 

Introduction  7 

Polystomidae  9 

Historical  Review  of  the  Family g 

The  Genus  Polystoma  i6 

Anatomy  and  Histology  of  the  Polystomidae 19 

Polystoma  orbiculare  Stunkard  1916  31 

Polystoma  opacum   Stunkard   1916  _ 34 

Polystoma  megacotyle  Stunkard  1916  37 

Polystoma  microcotyle   Stunkard    1916  39 

Polystoma  coronatum  Leidy   1888 40 

Polystoma  liassalli   Goto   1899 42 

Polystoma  oblongum   Wright  1879  44 

Key  to  the  Species  of  the  Genus  Polystoma 46 

Aspidogastridae    47 

Aspidogaster  conchicola  von  Baer  1827 48 

Cotylaspis  insignis  Leidy  1856  49 

Cotylaspis  cokeri  Barker  and  Parsons  1914. SO 

Classification  of  the  Family 57 

Paramphistomidae  _ 60 

Historical  Review  of  the  Family 60 

The  Genus  Alassostoma  64 

Alassostoma  magnum  Stunkard  1916. 66 

Alassostoma  parvum  Stunkard  1916 69 

The  Genus   Zygocotyle  _ 71 

Zygocotyle  ceratosa   Stunkard   I9i6._ 72 

Classification  of  the  Family 75 

Relation  of  the  Families  to  the  Order 80 

List  of  New   Species 84 

Bibliography    85 

Explanation  of  Plates  _ 91 


2871  XORTH  AMERICAN  POLYSTOMIDAE—STUNKARD 


INTRODUCTION 

The  knowledge  of  the  trematodes  of  North  America  is  verj'  scanty. 
Information  at  hand  consists  largely  of  brief  and  scattered  papers  and 
comprehensive  studies  on  the  morphology  of  the  larger  groups  are  want- 
ing. Such  studies  are  needed  as  contributions  to  the  knowledge  of  adult 
forms,  and  it  is  apparent  also  that  knowledge  of  the  anatomy  and  tax- 
onomy of  the  adult  is  demanded  in  the  solution  of  life  history  problems. 

This  paper  contains  the  results  of  a  study  on  the  structure 
and  classification  of  North  American  representatives  of  the  families 
Polystcmidae,  Aspidogastridae,  and  Paramphistomidae.  Because  of  cer- 
tain structural  and  developmental  features  these  three  families  are  of 
particular  interest  and  importance  not  only  in  the  taxonomy  but  also  in 
the  phylogeny  of  the  trematodes.  The  Polystomidae  differ  from  all  other 
known  Heterocotylea  in  that  they  are  endoparasitie ;  the  Aspidogastri- 
dae are  both  eetoparasitic  and  endoparasitie,  develop  both  directly  and 
by  means  of  an  intermediate  host,  and  in  the  adult  condition  are  para- 
sites of  both  vertebrates  and  molluscs ;  while  the  Paramphistomidae  are 
the  only  forms  retaining  a  primitive  posterior  sucker.  These  facts  are 
significant  and  it  is  probable  that  further  study  into  the  structure  and 
life  history  of  these  forms  will  throw  considerable  light  on  the  general 
problems  of  development  and  taxonomy  of  the  trematodes. 

During  the  past  three  years  the  writer  has  made  parasitological 
examinations  of  over  three  hundred  North  American  fresh-water  turtles. 
These  comprise  sixteen  species  collected  from  widely  scattered  localities. 
For  assistance  in  securing  this  material,  grateful  acknowledgments  are 
due  Dr.  N.  A.  Cobb  of  Washington,  D.  C,  Professor  A.  W.  Orcutt  of 
Denison  University,  Professor  W.  E.  Burge  of  the  University  of 
Illinois,  Professor  J.  E.  Ackert  of  Kansas  State  Agricultural  College, 
and  Professor  W.  W.  Cort  of  Macalester  College.  The  material  of 
Alassosioma  parvum  was  collected  and  turned  over  to  me  by  Mr.  T.  B. 
Magath.  A  type  specimen  of  Polystoma  coronatum  Leidy  from  the  U.  S. 
National  Museum  was  placed  at  my  disposal  for  study.  The  work  was 
begun  at  the  suggestion  of  Professor  Henry  B.  Ward  and  carried  on 
under  his  direction.  Part  of  the  material  used  in  the  investigation 
came  from  his  private  collection,  and  for  this  material  as  well  as  for 
criticisms  and  suggestions  in  the  course  of  the  work  the  writer  wishes  to 
express  his  appreciation. 


8.  ILLINOIS  BIOLOGICAL  MONOGRAPHS  [288 

All  the  forms  described  in  this  paper  were  studied  as  toto  mounts ; 
where  sufficient  material  was  available  sections  were  made,  and  many 
were  studied  alive.  The  importance  of  the  study  of  the  living  specimens 
can  not  be  overemphasized  as  the  best  method  of  tracing  the  excretory 
system.  Also,  by  observing  the  living  animal  as  it  moves,  it  is  possible 
to  measure  the  extent  of  normal  variation  in  form  that  occurs  in  a  single 
specimen  as  different  shapes  are  assumed  concomitant  with  the  move- 
ments of  the  animal ;  in  forms  with  such  soft  bodies  and  variable  shapes, 
a  study  of  preserved  material  alone  has  in  many  cases  given  false  con- 
ceptions concerning  morphological  relationships  of  organs  and  systems. 
In  toto  mounts  a  support  under  the  coverglass  is  necessary  to  prevent  it 
from  flattening  and  distorting  the  normal  shape  of  the  aspidogastrids 
and  to  avoid  crushing  the  caudal  disc  of  the  polystomes.  For  the  stain- 
ing of  specimens  to  be  mounted  in  toto,  better  results  were  obtained  by 
the  use  of  carmine  than  by  hematoxylin  stains.  For  staining  sections 
the  method  that  proved  most  valuable  was  to  use  the  hematoxylin  stains 
for  differentiating  the  nuclear  elements  and  various  plasma  stains  for 
counterstaining. 


289]  NORTH  AMERICAN  POLYSTOMIDAE—STUNKARD 


POliYSTOMIDAE 


HISTORICAL  REVIEW  OF  THE  FAMILY 


In  1758  Roesel  von  Rosenhof  described  and  figured  a  "leech"  from 
the  urinary  bladder  of  the  frog.  This  is  regarded  as  identical  with  the 
well  known  European  parasite  of  the  urinary  bladder  of  the  frog, 
described  by  Frohlich  (1791)  as  Linguahda  integerrimum.  M.  Braun 
(1792)  described  Planaria  iniciniilata  from  the  urinary  bladder  of  the 
green  water-frog  and  his  description  is  so  specific  that  there  can  be  no 
doubt  that  he  had  the  same  form  described  by  Frohlich  the  previous 
year.  Zeder  (1800)  founded  the  genus  Polystoma  to  contain  the  three 
species,  Linguatula  integerrimum  Frohlich  which  he  rechristened  Poly- 
stoma ranae,  P.  serratitm,  and  P.  pinguicola.  According  to  Stiles  and 
Hassall  (1908)  the  type  was  clearly  intended  to  be  P.  ranae  =  Planaria 
jtncinulata,  and  altho  Braun  had  described  the  form  correctly  with  the 
suckers  and  hooks  at  the  posterior  end  of  the  body,  Zeder  erroneously 
stated  in  his  characterization  of  the  genus  that  the  suckers  were  at  the 
anterior  end.  P.  serratum  had  been  designated  by  Frohlich  (1789)  as 
type  of  the  genus  Linguatula  and  P.  pinguicola  had  been  designated  by 
Treutler  (1793)  as  type  of  the  genus  Hexathyridium.  That  Zeder  was 
in  error  in  including  these  species  in  the  genus  Polystoma  was  demon- 
strated by  later  studies.  However  Rudolphi  (1809)  retained  them  in  the 
genus  Polystoma  and  listed  three  other  species:  P.  taenoides  Rud.,  P. 
denticulatum,  Rud.,  and  P.  venarum  (Treutler  1793)  Zeder  1803. 
Among  these  species,  it  is  probable  that  Treutler 's  description  was  of  an 
artifact  rather  than  a  parasite,  and  the  other  two  have  been  removed  to 
the  Linguatulidae. 

Polystoma  thynii  was  described  from  the  gills  of  Scomber  thynnus 
by  Delaroche'  (1811).  Rudolphi  (1819)  renamed  this  species  P.  duplica- 
tum  and  added  a  new  species  P.  ocellatum  from  the  throat  of  Emys 
europa.  This  species  is  regarded  as  identical  with  that  described  by 
Kuhl  and  Hassalt  (1822)  from  the  nasal  cavity  of  Ilalichelys  atra.  P. 
logiginis  was  described  by  delle  Chiaje  (1823)  from  Loligo  vulgaris. 
Blainville  (1828)  oriented  the  polystomes  correctly  and  transferred  P. 
integerrimum,  P.  ocellatum,  and  P.  thynii  to  a  new  genus  Hexaeotyle, 
naming  H.  thynii  as  type.  According  to  the  rules  of  zoological  nomen- 
clature, however,  the  genus  Polystoma  must  be  retained.    Kuhn  (1829) 


10  ILLINOIS  BIOLOGICAL  MONOGRAPHS  [290 

described  P.  appendiculatum  from  Squalus  catulus.  Dujardin  (1845) 
transferred  Diclibothrittm  crassicaudatum  Leuck.  1835  =  Diplobothrium 
armatum  Leuck.  1842  to  the  genus  Pohstoma,  and  listed  as  additional 
species,  P.  duplkatum,  P.  pinguicola,  P.  ocellatum,  P.  integerrimum,  and 
P.  appendiculatum.  Diesing  (1850)  named  P.  loliginis  and  P.  appendic- 
ulatum as  tj-pes  of  new  genera  Solenoeotjle  and  Onchocotyle.  He  re- 
moved P.  armatum  to  the  genus  Diclibothrium  Leuck.  and  retained  in 
the  genus  Polystoma  only  the  species  P.  integerrimum  and  P.  ocellatum. 
The  genus  Polystoma  together  with  the  genera  Tetrastomum,  Gry- 
porhynchus,  Hexathyridium,  Notocotyle,  Aspidocotyle,  and  Aspidogas- 
ter  were  included  by  the  same  author  in  the  tribe  Polycotylea. 

In  his  revision  Diesing  (1859)  reduced  the  trematodes  to  the  rank 
of  a  tribe  and  divided  the  group  into  three  subtribes:  Acotylea,  Coty- 
lophora,  and  Plectanophora.  The  second  of  these  subtribes  he  subdivi- 
ded into  three  families :  Monocotylea,  Tricotylea,  and  Polycotylea.  The 
last  of  these  corresponds  almost  identically  with  his  former  tribe  Poly- 
cotylea. He  rejected  Gryporhynchus.  and  added  the  genera  Ancyroceph- 
alus,  Plagiopeltis,  Heptastomum,  Onchocotyle,  Cyclocotyle,  and  Solen- 
oeotyle.  In  the  family  Polycotylea  he  recognized  two  subfamilies: 
Aplacocotylea  with  the  suckers  set  directly  in  the  body,  and  Placocotylea 
with  the  suckers  set  in  a  median  posterior  plate.  In  the  latter  he  in- 
cluded the  genera  Onchocotjde,  Polystoma,  Cyclocotyle,  Aspidocotyle, 
Aspidcgaster,  and  Solenocotyle. 

Then  followed  the  great  work  of  van  Beneden  (1858)  with  an  ex- 
perimental demonstration  of  the  "direct"  development  of  the  many- 
suckered  ectoparasitic  trematodes,  and  the  "indirect"  development  of 
the  distomes.  For  these  two  groups  he  proposed  the  names  Monogenea 
and  Digenea.  In  the  former  he  recognized  two  families:  the  Tristomi- 
dae  with  a  single  posterior  sucker,  and  the  Polystomidae  with  several 
posterior  suckers.  In  the  Polystomidae  he  included  the  genera  Polystoma, 
Diplozoon,  Octobothrium,  Axine,  Onchocotyle,  Calceostoma,  and  Gyro- 
dactylus. 

Later  van  Beneden  and  Hesse  (1863)  made  the  genera  Oetocotyle 
(  =  Octobothrium),  Udonella,  and  Gyrodactjdus  types  of  new  families, 
thus  increasing  the  number  of  families  to  five.  Many  additional  genera, 
both  old  and  recently  described,  were  now  for  the  first  time  placed  with 
the  Monogenea.  But  in  the  family  Polystomidae  these  authors  retained 
only  two  genera,  Polystoma  and  Erpocotyle ;  and  in  the  genus  Polystoma 
was  listed  only  a  single  species,  P.  integerrimum. 

Taschenberg  (1879)  reverted  to  the  earlier  classification  of  van 
Beneden  and  adopted  the  division  of  the  monogenetic  trematodes  into  two 


291]  NORTH  AMERICAN  POLYSTOMIDAE—STUNKARD  11 

groups  Tristomeae  and  Polystomeae,  which  he  I'egarded  as  families 
Under  the  Polystomeae  as  subfamilies  he  listed  Polystomidae,  Octoboth- 
ridae  (  =  Octocotylidae),  Gyrodactylidae,  and  the  new  subfamily  Miero- 
cotylidae ;  the  latter  including  Microcotyle,  Axine,  Gastrocotyle  and  the 
entirely  unlike  genera,  Aspidogaster,  Cotylaspis  and  Aspidocotyle.  To 
the  Polj'stomidae  he  added  the  genera  Onehocotj'le  and  Diplobothrium, 
and  in  the  genus  Polystoma  included  the  two  species  P.  integerrimum 
and  P.  ocellatum. 

In  regard  to  the  previously  mentioned  forms  St.  Remy  (1891)  fol- 
lowed the  family  and  subfamily  divisions  of  Taschenberg,  tho  adding 
new  genera  to  each  of  the  subfamilies  and  removing  Aspidogaster,  Coty- 
laspis, and  Aspidocotyle  from  the  Microcotylidae.  To  the  Polystomidae, 
Wright  and  Macallum  had  added  the  genus  Sphyranura,  and  in  the  genus 
Polystoma  were  listed  the  new  species  P.  dbloagum  Wright  and  P.  coro- 
natum  Leidy. 

Increased  knowledge  of  the  trematodes  disclosed  so  many  exceptions 
to  their  classification  according  to  life  history  that  Montieelli  (1892) 
proposed  a  new  arrangement  of  the  group,  based  on  morphological  char- 
acters. To  contain  the  forms  previously  classed  as  Monogenea,  he  pro- 
posed the  suborder  Heterocotylea.  He  raised  the  Monocotylidae  and 
Gyrodactylidae  from  subfamily  to  family  rank,  making  five  families  in 
the  Heterocotylea.  In  the  family  Polystomidae  he  retained  the  sub- 
families Polystominae,  Oetocotylinae,  and  Mierocotylinae  of  former 
authors. 

So  far  as  the  Polystomidae  are  concerned,  the  synopsis  of  Pratt 
(1900)  does  not  differ  from  that  of  St.  Remy  and  Montieelli. 

Later  Montieelli  (1903)  worked  out  a  new  classification  of  the 
Heterocotylea,  separating  the  forms  on  the  basis  of  differences  in  the  ad- 
hesive apparatus.  He  arranged  the  families  in  two  tribes,  Oligocotylea 
and  Polj'cotylea,  the  former  containing  the  forms  with  few  suckers  and 
the  latter  those  with  many  suckers.  This  division  he  says  is  not  of  great 
systematic  importance  but  may  be  of  practical  value  in  the  identification 
of  families.  In  the  Oligocotylea  he  included  the  families  Tristomidae, 
Monocotylidae,  Udonellidae,  Calceostomidae,  Gyrodactylidae,  and  Dieo- 
tylidae ;  and  in  the  Polycotylea  the  families  Polystomidae,  Octocotylidae, 
Hexacotylidae,  Platycotylidae,  Pleurocotylidae,  and  Microcotylidae. 
Among  these  the  Udonellidae,  Octocotylidae,  and  Microcotylidae  are 
raised  from  subfamily  to  family  rank,  and  the  Calceostomidae,  Dieoty- 
lidae,  Hexacotylidae,  Platycotylidae,  and  Pleurocotylidae  are  new  fam- 
ilies. The  family  Polystomidae  contained  the  single  genus  Polystoma 
with  the  species  P.  integerrimum,  P.  ocellatum,  P.  oblongum,  P.  coro- 
natum,  and  P.  hassalli. 


12  ILLINOIS  BIOLOGICAL  MONOGRAPHS  [292 

Discussing  the  classification  of  ilontieelli,  Odhner  (1912)  stated  that 
he  considered  the  number  of  suckers  of  secondarj'  importance  and  the 
system  based  on  them  therefore  lacking  in  fundamental  systematic  sig- 
nificance. Accordingly  he  rejected  the  work  of  !Monticelli,  and  using  the 
older  classification  of  Monogenea,  divided  the  forms  within  the  group  on 
the  basis  of  differences  in  the  female  reproductive  ducts.  He  discussed 
the  relationship  of  the  ducts  of  the  female  genital  sj-stem  in  various  trema- 
tode  and  cestode  genera,  and  stated  that  he  was  convinced  as  was  claimed 
by  Stieda  that  Laurer's  canal  of  the  trematodes  should  be  regarded  as 
homologous  with  the  vagina  of  the  eestodes.  Intervening  authors,  Looss 
(1893),  Goto  (1894)  and  several  other  writers,  had  considered  Laurer's 
canal  of  the  Malacocotylea  as  homologous  ^vith  the  genito-intestinal  canal 
of  certain  Heterocotylea,  and  not  with  the  vagina  of  the  eestodes.  Odh- 
ner argued  that  Laurers  canal  was  the  primitive  vagina  of  the  trema- 
todes and  that  there  had  been  a  change  of  vaginal  function  from  this 
canal  to  the  terminal  part  of  the  uterus,  with  the  resulting  degeneration 
of  the  former  duct.  It  now  served  in  his  opinion  only  to  carry  off  excess 
spermatozoa,  together  with  yolk  and  shell  substance  not  used  in  the  for- 
mation of  the  eggs.  He  adds  that  there  is  no  evidence  on  which  to  base 
an  explanation  of  the  transfer  of  the  seat  of  vaginal  function  from 
Laurer's  canal  to  the  terminal  part  of  the  uterus;  it  must  onty  be  accepted 
as  a  fact. 

According  to  Odhner,  in  the  group  of  moncgenetic  trematodes,  two 
very  different  structures  are  included  under  the  term  vagina.  One  pres- 
ent in  the  Tristomidae,  ISIonocotylidae,  and  Gyrodaetylidae  opens  to  the 
exterior  on  the  left  side  of  the  ventral  surface,  and  at  the  inner  end  is 
enlarged  to  form  the  seminal  receptacle.  This  tube  he  considered  homo- 
logous to  the  vagina  of  the  eestodes  and  Laurer's  canal  of  the  digenetic 
trematodes.  The  other  structures  which  he  did  not  consider  homologoiis 
to  this  true  vagina  were  the  ducts  of  the  Octocotylidae,  Polystomidae, 
and  Microcotylidae,  which  function  as  vaginae  and  open  into  the  vitelline 
collecting  ducts.  These  are  paired  and  open  to  the  surface  either  ven- 
trally,  laterally,  or  dorsally.  Contending  that  they  had  arisen  sui  generis, 
he  proposed  for  them  the  name  "ductus  vaginalis."  Considering 
the  question  of  whether  the  paired  or  unpaired  condition  of  these 
ducts  was  primitive,  he  argued  that  originally  the  duct  was 
unpaired  and  opened  ventrally;  that  the  opening  became  divided 
and  the  duct  split,  therefore  the  Y-shaped  duet  of  Rajonchoeotyle 
must  be  considered  as  a  stage  in  the  development  of  the  paired  condition 
of  the  ducts.  A  further  separation  would  give  the  lateral  openings  of 
Polystoma.  In  the  Mierocotj'lidae  the  openings  have  migrated  dorsally 
and  fused  producing  a  single  dorsal  tube.  Odhner  could  find  no  homo- 
logue  for  the  genito-intestinal  canal  and  since  he  maintained  that  it  was 


293]  NORTH  AMERICAN  POLYSTOMIDAE—STUNKARD  13 

not  homologous  with  Laurer's  canal,  concluded  that  it  had  arisen  sui 
generis. 

On  the  basis  of  these  differences  in  the  female  genital  ducts  he 
divided  the  Monogenea  into  two  suborders :  Monopisthoeotylea  and  Poly- 
opisthocotylea.  The  former  is  characterized  by  the  absence  of  the  genito- 
intestinal  canal,  the  presence  of  a  "true  vagina"  and  a  single  pos- 
terior organ  of  attachment;  the  latter  by  the  presence  of  the  genito- 
intestinal  canal,  "ductus  vaginalis,"  many  posterior  adhesive  organs, 
and  the  absence  of  a  "true  vagina."  In  the  Monopisthoeotylea 
he  included  the  families  Tristomidae,  Monocotylidae,  Udonellidae 
and  Gyrodactylidae ;  and  in  the  Polyopisthocotylea  the  families 
Polystomidae,  Microcotylidae  and  Octocotylidae.  He  pointed  out  that 
by  the  removal  of  the  genus  Sphyranura,  the  Oligoeotylea,  the  first  of 
Monticelli's  tribes  agrees  entirely  with  his  suborder  Monopisthoeotylea. 
In  the  second  of  Monticelli's  tribes,  however,  the  Diclidophorinae,  to- 
gether with  the  genera  Dactylocotyle  and  Hexacotyle,  should  be  re- 
moved from  the  Octocotylidae  and  placed  with  the  Microcotylidae,  since 
they  more  nearly  agree  with  the  latter  forms  in  internal  structure. 

The  next  year  Odhner  (1913)  reaffirmed  his  idea  of  the  homology 
of  the  vagina  of  the  cestodes  and  Laurer's  canal  of  the  distomes, 
but  explained  therewith  that  his  denial  of  the  homology  of  the 
genito-intestinal  canal  and  Laui'er's  canal  had  been  based  on  an  error  of 
Cerfoutaine  in  describing  an  unpaired  vagina  as  present  in  the  genus  Dac- 
tylocotyle. On  examination  of  this  genus  he  had  found  that  a  "true 
vagina"  was  absent,  and  concluded  that  the  "true  vagina"  of  the  Mono- 
pisthoeotylea which  he  had  homologized  with  Laurer's  canal  was  never 
present  together  with  the  genito-intestinal  canal.  From  this  he  decided 
that  the  "true  vagina"  was  homologous  with  the  genito-intestinal  canal 
and  therefore  with  Laurer's  canal.  Now  maintaining  the  homology  of 
the  "true  vagina"  and  the  genito-intestinal  canal  he  is  in  my  opinion 
obliged  to  dismiss  the  presence  or  absence  of  the  genito-intestinal  canal 
as  a  basis  of  difference  between  his  suborders,  and  explain  why  in  one 
group  this  canal  opens  to  the  exterior  on  the  ventral  side  of  the  body 
and  in  the  other  opens  into  the  intestine.  His  homology  of  the  "true 
vagina"  and  the  genito-intestinal  canal  is  a  most  serious  error  since  it 
would  invalidate  the  distinguishing  feature  which  separates  the  two 
suborders. 

I  propose  to  show  that  the  organ  which  functions  as  a  vagina  is 
homologous  in  all  the  monogenetic  trematodes,  and  that  there  can  be  no 
division  of  the  group  on  the  basis  of  differences  suggested  by  Odhner. 
In  fact,  the  work  of  Odhner  is  based  on  an  incorrect  assumption  and 
false  homologies.  Starting  with  the  assumption  that  Laurer's  canal  is 
homologous  to  the  vagina  of  the  cestodes,  he  has  missed  the  truth  in  his 


14  ILLIXOIS  BIOLOGICAL  MOXOGRAPHS  [294 

entire  discussion  and  when  at  a  loss  to  explain  a  structure  has  derived  it 
sui  generis.  His  later  paper  (1913)  admitting  the  homology  of  Laurer's 
and  the  genito-intestinal  canals  corrected  one  mistaken  contention,  but 
his  separation  of  the  female  copulatory  ducts  into  a  true  vagina  and 
"caualis  vaginalis"  seems  entirely  without  foundation.  There  is  no  evi- 
dence to  support  the  idea  that  the  single  vagina  is  not  homologous  to  the 
paired  vaginae.  In  fact,  Odhner  described  the  paired  vaginae  as  arising 
by  the  division  of  a  single  unpaired  tube,  probably  ventral  in  position. 
He  derived  this  tube  sui  generis,  and  cited  no  reason  why  it  is  not  homo- 
logous with  the  ventral  unpaired  vagina  of  the  Monopisthocotylea.  Fur- 
ther lie  gives  no  means  of  distinguishing  between  the  two. 

Looss  (1893)  presented  a  strong  argument  to  prove  that  Laurer's 
canal  is  not  a  vagina,  nor  homologous  to  the  vagina  of  the  cestodes. 

Goto  (1894)  reveiewed  the  literature  up  to  that  date  and  gave  a 
careful  and  detailed  study  of  the  canalis  gcnito-intestinalis.  Making  a 
very  clear  and  comprehensive  analysis  of  the  question  and  summarizing 
evidence  from  a  wide  study  of  eetoparasitic  forms,  he  concluded  that  the 
genito-intestinal  canal  and  Laurer's  canal  are  homologous  and  that 
neither  are  homologous  with  the  vagina  of  the  Monogenea.  He  showed 
that  in  the  group  there  is  a  perfect  series  of  vaginae  from  a  truly  paired 
to  a  truly  unpaired  condition.  He  discussed  the  idea  of  Braun  who  re- 
garded the  presence  of  a  single  vagina  as  the  result  of  a  simple  atrophy 
of  one  of  the  originally  paired  vagiua,  with  the  conclusion  that  the  rela- 
tions of  the  ducts  "point  strongly  to  the  view  that  the  unpaired  vagina 
has  been  formed  by  the  union  and  subsequent  displacement  of  the  ori- 
ginally paired  vaginae,  and  not  as  Braun  supposes  by  the  atrophy  of  one 
of  them." 

In  the  present  study,  the  histological  character  and  the  relative  posi- 
tion and  relationships  of  the  ducts  of  the  female  system  support  the  con- 
tention of  Looss  and  Goto  that  Laurer's  canal  is  homologous  with  the 
genito-intestinal  canal,  and  affords  no  evidence  that  these  duets  have  any 
further  homologue.  A  review  of  the  literature  and  the  study  of  the  ducts 
in  the  three  families  discussed  in  this  paper  has  convinced  me  that 
Laurer's  canal  is  homologous  to  the  genito-intestinal  canal ; and  the  vagina 
of  the  Monopisthocotylea  is  homologous  with  the  originally  single,  sub- 
sequently paired,  and  secondarily  fused  vaginae  of  the  Polyopisthocotylea. 
It  makes  no  difference  whether  the  single  or  paired  condition  is  regarded 
as  primitive.  Given  a  single  unpaired  vagina  as  described  by  Odhner 
for  the  Monopisthocotylea ;  by  a  division  of  the  external  part  and  subse- 
quent lateral  migration  of  the  openings,  the  paired  vaginae  of  the  Poly- 
opisthocotylea are  explained.  These  ducts  entering  the  body  from  the 
sides,  lying  parallel  with  the  vitelline  ducts  and  discharging  into  the 


295]  NORTH  AMERICAN  POLYSTOMIDAE—STUNKARD  IS 

same  cavity,  became  fused  at  their  internal  ends  with  the  vitelline  ducts 
and  this  union  continued  outward  to  the  location  where  the  vitelline 
ducts  turn  toward  the  follicles  and  the  vaginae  branch  off  to  open  to  the 
exterior.  The  advantage  of  a  single  duct  over  two  ducts  lying  side  by 
side  is  obvious,  and  the  fusion  of  two  parallel  ducts  is  not  uncommon  in 
other  groups.  With  a  further  dorsal  migration  of  the  opening  of  the 
vaginae  there  would  be  a  separation  of  the  vitelline  and  vaginal  canals 
and  a  dorsal  fusion  of  the  vaginae  would  give  the  single  dorsal  vagina  of 
Octobothrium,  Axine,  and  Microcotyle.  The  earlier  fusion  of  the  vitel- 
line and  vaginal  canals  would  retard  the  secondary  fusion  of  the  internal 
ends  of  the  dorsal  vaginae  and  this  explains  the  single  dorsal  pore  and 
internally  paired  vagina  of  Axine  heterocerca  which  is  used  by  Odhner 
as  an  argument  supporting  his  idea  that  in  the  Monogenea  two  different 
structures  are  included  under  the  term  vagina. 

I  agree  with  Odhner  that  the  seminal  receptacles  of  Sphyranura  are 
homologous  to  the  paired  vaginae  of  Polystoma,  and  that  this  furnishes 
a  splendid  example  of  the  change  whereby  the  terminal  part  of  the  uterus 
has  assumed  the  eopulatory  function.  It  may  be  that  further  specializa- 
tion in  this  direction,  due  to  the  endoparasitic  habit  and  self  fertilization, 
may  explain  the  absence  of  the  vagina  of  the  distomes. 

It  now  remains  only  to  account  for  the  absence  of  the  genito-in- 
testinal  canal  in  the  Monopisthocotylea.  Odhner  stated  that  this  struc- 
ture is  homologous  with  Laurer's  canal,  and  in  his  (1912)  paper  called 
attention  to  the  fact  that  Laurer's  canal  is  a  "rudimentary  organ" 
which  serves  no  essential  function.  The  vestigeal  character  of  Laurer's 
canal  is  believed  in  by  most  writers — Looss,  Monticelli,  Brandes,  Goto, 
etc.  This  structure  is  entirely  lacking  in  some  distome  groups  and  in 
others  is  represented  by  a  blind  sac  opening  from  the  ootype.  Since  the 
genito-intestinal  canal  is  admittedly  homologous  to  Laurer's  canal  and 
the  latter  is  known  to  be  a  vestigeal  structure,  it  appears  reasonable  to 
suppose  that  it  has  degenerated  in  the  Monopisthocotylea. 

There  is  a  possibility  that  the  Monopisthocotylea  instead  of  having 
lost  a  genito-intestinal  canal  may  have  arisen  from  a  group  of  the  Tur- 
bellaria  which  had  no  homologous  structure,  but  this  explanation  seems 
very  improbable.  Haswell  (1907)  described  in  certain  Australian  poly- 
clads  a  tube  which  formerly  had  been  considered  an  accessory  or  dorsal 
vagina  but  which  in  certain  forms  opened  into  the  intestine.  The  pres- 
ence of  this  genito-intestinal  canal  in  polyclads,  he  says, ' '  strengthens  the 
contention,  so  ably  supported  by  Goto,  that  the  genito-intestinal  canal 
and  not  the  vagina  of  the  Heterocotylea  is  the  equivalent  of  the  Laurer's 
canal  of  the  Malacocotylea." 

The  absence  of  the  genito-intestinal  canal  in  the  Monopisthocotylea 


16  ILLINOIS  BIOLOGICAL  MONOGRAPHS  [296 

is  undoubtedly  a  feature  of  distinct  taxonomic  importance,  and  the  work 
of  Odhner  is  an  advance  step  in  the  formation  of  a  natural  system  and 
the  final  classification  of  the  monogenetie  forms.  Since  the  arrangement 
of  Monticelli,  based  on  the  character  of  the  adhesive  apparatus,  so  nearly 
agrees  with  that  of  Odhner  which  in  reality  is  based  on  the  presence  or 
absence  of  a  genito-intestinal  canal,  it  appears  that  both  these  features 
are  of  large  importance  in  the  taxonomy  of  the  group.  Present  evidence 
is  insufiBcient  to  decide  which  is  of  greater  significance.  Further  study 
may  show  that  there  is  complete  agreement  in  classifications  based  on 
both  features. 

Odhner  (1912)  argued  that  the  removal  by  Monticelli  of  Sphyranura 
from  the  family  Polystomidae  on  the  basis  of  the  difference  in  number 
of  suckers  was  not  justified.  As  previously  stated,  the  writer  agrees  with 
Odhner  that  the  seminal  receptacles  of  Sphyranura  are  homologous  with 
the  vaginae  of  Polystoma,  and  the  agreement  in  type  of  genital  ducts  in- 
dicates a  closer  relationship  between  these  genera  than  is  assigned  in  the 
system  of  Monticelli.  Sphyranura  undoubtedly  should  be  placed  with  the 
Polyopisthocotylea.  There  are,  however,  wide  and  fundamental  differ- 
ences between  it  and  the  genus  Polystoma,  and  while  future  researches 
may  discover  intermediate  forms  which  will  make  it  possible  to  include 
them  with  certainty  in  a  single  family,  for  the  present  such  a  grouping  is 
hardly  justified  and  the  two  families  should  be  retained,  altho  the  name 
Dicotylidae  of  Monticelli  does  not  conform  to  the  rules  of  zoological 
nomenclature. 

THE  GENUS  POLYSTOMA 

The  family  Polystomidae  as  considered  in  this  paper  contains  only 
the  genus  Polystoma.  The  members  of  this  genus  are  widely  distributed, 
species  having  been  described  from  aU  the  continents  except  South 
America.  The  species  are  not  only  widely  distributed  geographically, 
but  also  vary  widely  in  type  of  host  and  in  locatisn  within  the  host. 
They  are  parasitic  in  the  urinary  bladder  of  frogs  and  toads  and  on  the 
gills  of  frog  larvae,  and  also  infest  the  urinary  bladder  and  pharyngeal 
cavity  of  many  species  of  turtles. 

The  structure  and  development  of  Polystoma  integerrimum  has  been 
investigated  by  Stieda  (1870),  ZeUer  (1872  and  1876),  WiUemoes-Suhm 
(1872),  Halkin  (1902),  Goldschmidt  (1902),  and  Andre  (1910).  Zeller 
(1876)  described  two  forms  of  P.  integerrimum,  one  which  became  ma- 
ture in  the  urinary  bladder  of  the  frog,  and  the  other  which  became,  ma- 
ture on  the  gills  of  the  frog  tadpole.  These  two  forms  of  the  parasite 
show  wide  differences  in  size  and  internal  structure.  The  form  which 
becomes  mature  in  the  urinary  bladder  is  much  larger,  has  a  lobed 
testis,  external  vaginae,  and  a  long  coiled  uterus  which  contains  many 


297]  NORTH  AMERICAN  POLYSTOMIDAE—STUNKARD  17 

eggs.  The  form  maturing  on  the  gills  of  the  tadpole  has  a  spherical 
testis,  lacks  external  vaginae  and  a  long  coiled  uterus,  and  has  a  small 
uterine  cavity  in  which  a  single  egg  develops.  Halkin  and  Goldschmidt 
liave  investigated  the  early  stages  in  this  form,  but  the  writer  has  been 
unable  to  find  any  reference  to  work  on  the  later  larval  stages.  The 
findings  of  Zeller  are  so  unusual  that  one  is  led  strongly  to  suspect  he 
confused  two  different  species. 

The  descriptions  of  P.  ocellatum  by  Rudolphi  (1819)  and  Kuhl  and 
Hassalt  (1822)  are  very  brief;  that  by  Willemoes-Suhm  (1872)  contains 
one  plate,  and  Looss  (1885)  figured  only  the  structures  at  the  distal  ends 
of  the  excretory  tubules. 

The  description  of  P.  oblongum  Wright  (1879)  contains  sufficiently 
detailed  information  for  a  specific  diagnosis  and  is  illustrated  by  three 
figures.  Stafford  (1905)  reported  P.  oblongum  from  the  palate  of  Chry- 
semys  picta  and  the  same  location  in  Chelydra  serpentina,  but  since 
Wright  originally  described  the  species  from  the  urinary  bladder  of 
Aramochelys  odoratus,  Braun  reviewing  Stafford's  article  considered 
the  form  from  the  oral  cavity  as  a  different  species.  The  form  described 
by  Leidy  as  P.  ohlongum,  was  reinvestigated  by  Goto  (1899)  and  proved 
to  be  a  different  species  from  that  described  by  Wright,  but  the  material 
he  reports  was  in  such  a  poor  state  of  preservation  that  renewed  study 
was  impossible  and  so  the  form  must  remain  unknown. 

Leidy 's  (1888)  description  of  P.  coronatum  is  so  brief  that  it  is  al- 
most valueless ;  a  type  specimen  mounted  as  a  toto  preparation  has  been 
available  for  the  present  study  and  many  additional  points  of  structure 
are  added  to  the  original  description. 

P.  hassalli  was  described  by  Goto  (1899)  from  the  urinary  bladder  of 
Cinostemum  pennsylvanicum  and  has  been  collected  by  the  writer  from 
the  urinary  bladder  of  Aromochelys  odoratus,  A.  carinatus,  and  Chelydra 
serpentina,  as  well  as  from  Cinostemum  pennsylvanicum.  Additional 
data  correct  and  supplement  the  description  of  Goto. 

Johnston  (1912)  described  P.  iulliense  from  the  urinary  bladder  of 
two  species  of  Hyla  from  New  South  Wales,  Australia.  Beauchamp 
(1913)  described  P.  alluaudi  from  an  unknown  batrachian  from  the  lower 
prairies  of  Kinangop,  Africa ;  the  material  was  collected  by  the  African 
expedition  of  Alluaud  and  Jeannel.  Stewart  (1914)  described  P.  kachu- 
gae  from  the  urinary  bladder  of  the  water  tortoise,  Kachuga  lineata,  at 
Lucknow,  India. 

In  the  genus  Polystoma  present  evidence  supports  the  validity  of  the 
following  described  species  listed  in  the  order  of  description : 

P.  integerrimum  Frolich  1791.  From  the  urinary  bladder  of  froga 
and  toads  and  the  gills  of  frog  larvae ;  Europe. 


18  ILLINOIS  BIOLOGICAL  MONOGRAPHS  [298 

P.  oceUatum  Rudolphi  1819.  From  the  throat  and  nasal  canity  of 
Emys  europa  and  Halichelys  atra;  Europe. 

P.  oblongum  Wright  1879.  From  the  urinary  bladder  of  Aromo- 
chelys  odoratus;  North  America. 

P.  coronatum  Leidy  1888.  From  the  fauces  of  the  terrapin;  North 
America. 

P.  hassalli  Goto  1899.  From  the  urinary  bladder  of  Cinosternum 
pennsylvanicum,  Aromochelys  odoratus,  A.  carituitus,  and  Chelydra  ser- 
pentina; North  America. 

P.  bulliense  Johnston  1912.  From  the  urinary  bladder  of  Hyla 
phyllochros  and  H.  Lesueurii;  Australia. 

P.  alluaudi,  Beauchamp  1913.  From  an  unknown  batrachian; 
Africa. 

P.  Icachugae  Stewart  1914.  From  the  urinary  bladder  of  Kachuga 
lineata;  India. 

In  the  present  work  evidence  is  submitted  to  justify  the  inclusion  of 
the  following  new  species: 

P.  orbiculare  Stunkard  1916.  From  the  urinary  bladder  of  Pseu- 
demys  scripta  and  Chrysemys  marginata;  North  America. 

P.  opacum  Stunkard  1916.  From  the  pharynx  of  Trionyx  ferox  and 
Malacoclemmys  lesueurii;  North  America. 

P.  megacotyle  Stunkard  1916.  From  the  mouth  of  Chrysemys  mar- 
ginata; North  America. 

P.  microcotyle  Stunkard  1916.  From  the  mouth  of  Chrysemys  mar- 
ginata; North  America. 

With  the  exception  of  P.  integerrimum,  the  members  of  the  genus  are 
very  rarely  found  and  the  number  of  individuals  discovered  is  verj-  small. 
Wright  described  P.  oblongum  from  two  specimens;  Leidy,  P.  corona- 
tum from  four  specimens ;  Johnston  had  sixteen  specimens  of  P.  hulliense; 
Beauchamp  described  P.  alluaudi  from  a  single  specimen;  Stewart  had 
only  two  specimens  of  P.  kachugae.  The  writer  had  only  a  limited  num- 
ber of  individuals  of  any  species;  P.  microcotyle  was  described  from  a 
single  specimen;  P.  orbiculare  from  nine  specimens;  P.  opacum  and  P. 
megacotyle  each  from  three  specimens.  Because  of  the  limited  amount 
of  material,  it  has  been  impossible  to  attempt  special  technique  to  differ- 
entiate the  various  organ  systems,  and  the  descriptions  are  therefore  in- 
complete in  certain  particulars.  The  general  morphological  features  are 
however  described  in  sufficient  detail  that  clear  specific  diagnoses  can  be 
made,  and  in  certain  instances  the  finer  structure  and  histology  of  the 
organs  has  been  described. 


299]  NORTH  AMERICAN  POLYSTOMIDAE—STUNKARD  19 

ANATOMY   AND   HISTOLOGY   OF   THE   POLYSTOMIDAE 

The  species  that  have  been  included  in  the  genus  Polystoma  show  a 
much  wider  range  of  structural  variation  than  is  usually  present  in  a 
natural  genus.  There  are  wide  differences  in  the  character  of  digestive 
and  reproductive  systems,  and  variation  exists  in  the  type  of  adhesive 
apparatus. 

There  is  wide  variation  in  size ;  P.  integerrimum,  the  largest  known 
species  measures  up  to  12  mm.  in  length,  and  P.  hassalli  is  only  1.3  to  2 
mm.  in  length.  The  width  is  one-third  to  one-fifth  of  the  total  length. 
All  the  worms  that  have  been  included  in  this  genus  have  a  flattened, 
elongate  oval  body  which  at  the  posterior  end  bears  a  large  ventral 
muscular  disc  or  cotylophore.  The  body  is  more  or  less  pointed  at  the 
anterior  end  and  at  the  posterior  end  may  or  may  not  have  a  constriction 
just  before  the  attachment  of  the  caudal  disc.  As  in  all  trematodes  the 
shape  is  subject  to  considerable  variation  as  the  animal  elongates  and 
contracts.  Locomotion  is  accomplished  by  attaching  the  anterior  sucker 
and  then  bringing  the  caudal  disc  forward;  as  a  result  of  the  terminal 
attachments  and  the  "looping"  method  of  progression,  the  dorsal  line  of 
the  body  is  more  or  less  arched  and  the  ventral  surface  is  concave.  In 
certain  species  at  the  openings  of  the  vaginae  on  the  lateral  or  ventro- 
lateral margins  of  the  body,  there  are  prominent  swellings,  the  "Seiten- 
wiilste ' '  of  Zeller.  These  structures  are  not  present  in  any  of  the  known 
North  American  species. 

Organs  of  Attachment. — -The  caudal  disc  bears  on  its  ventral  face 
the  chief  organs  of  attachment.  These  consist  of  suckers  and  hooks,  the 
former  arranged  in  pairs,  three  suckers  on  each  side  of  the  median  line. 
The  two  posterior  suckers  are  close  together  and  those  of  the  middle  pair 
are  separated  by  a  considerable  distance,  while  the  anterior  pair  may  or 
may  not  be  near  each  other.  In  all  previously  reported  forms  except  P. 
alluaudi,  the  anterior  suckers  are  separated  by  a  considerable  distance, 
giving  the  disc  the  shape  described  by  Leidy  as  eordiform  (Fig.  27).  In 
the  single  specimen  of  P.  alluaudi  described  by  Beauchamp,  both  the 
caudual  and  cephalic  suckers  are  separated,  while  those  of  each  side  are 
contiguous.  In  P.  orhiculare  the  anterior  suckers  are  in  the  same  close 
proximity  as  the  caudal  pair,  and  each  sucker  of  the  disc  is  separated 
from  the  two  adjacent  to  it  by  uniform  distances,  making  a  perfect  circle 
of  suckers  (Fig.  1).  In  the  six  species  described  by  the  writer  these 
suckers  are  complicated  structures,  set  more  or  less  deeply  in  the  paren- 
chyma of  the  caudal  disc.  Their  structure,  character  of  insertion,  mus- 
cular attachments,  and  relation  to  the  surrounding  tissue  indicate  that 
they  are  protrusible  and  retractile,  and  in  fact  such  movements  may  be 
observed  by  watching  the  live  worm. 


20  ILLINOIS  BIOLOGICAL  MOXOGRAPHS  [300 

The  suckers  are  cup  shaped  (Fig.  34),  and  in  all  the  species  describ- 
ed in  this  paper  are  constructed  on  an  elaborate  cuticular  framework. 
According  to  Zeller  the  sucker  forms  as  a  ridge  around  a  larval  booklet 
and  later  sinks  into  the  parenchyma,  and  this  method  of  origin  explains 
the  cuticular  covering  of  the  external  and  internal  surfaces  of  the  cup. 
Running  across  between  these  cuticular  membranes,  there  are  short  re- 
fractive fibers  which  constitute  the  mass  of  the  wall  of  the  sucker  (Fig. 
35).  Wright  and  Macallum  (1887)  describing  similar  fibers  in  the  walls 
of  the  suckers  of  Sphyranura  say,  "Instead  of  the  substance  of  the 
sucker  being  formed  of  muscular  fibers  disposed  in  three  directions,  and 
capable  of  modifying  the  shape  of  the  cavity,  as  in  the  distomes,  it  is  not 
possessed  of  contractility  in  Sphyranura  (and  probably  in  Polystoma), 
and  is  formed  of  prismatic  fibers,  rather  of  a  supportive  than  a  muscular 
character,  arranged  perpendicularly  between  the  concave  and  convex 
limiting  membranes  of  the  suckers."  Goto  (1894)  described  similar 
fibers  in  the  suckers  of  Axine,  Microcotyle,  Octocotyle,  Dielidophora, 
Hexacotyle,  and  Onchocotyle  and  considered  them  to  be  more  of  an  elastic 
than  a  contractile  nature.  They  are,  he  states,  different  from  the  ordi- 
nary muscular  fibers  of  the  body  and  from  those  of  the  suckers  of  the 
Tristomidae  and  Monocotylidae,  as  well  as  from  those  of  the  anterior 
sucker  of  Onchocotyle,  both  in  optical  charactei-s  and  in  reaction  toward 
staining  fluids.  The  structure  of  the  suckers  in  these  forms  and  their 
mode  of  operation  are  discussed  by  Goto  at  considerable  length,  but  as  the 
suckers  he  described  are  constructed  on  a  different  type  of  cuticular 
framework  from  that  present  in  the  genus  Polystoma,  obviously  the  type 
of  suctorial  action  is  different. 

In  all  the  species  described  in  this  paper,  the  fibers  which  form  the 
walls  of  the  posterior  suckers  are  similar  to  those  described  by  Wright 
and  Macallum  and  Goto;  the  cuticular  framework  is  also  flexible  and 
elastic,  but  is  of  a  different  type  from  that  described  by  Goto.  In  the 
polystomes  investigated  by  the  writer,  with  the  exception  of  P.  integer- 
rimum,  the  sucker  consists  of  three  sections  or  zones  which  may  be  desig- 
nated as  basal,  intermediate,  and  external  or  distal  (Fig.  36).  The  ex- 
ternal part  or  rim  of  the  sucker  is  supported  by  numerous  cuticular  rods 
formed  by  the  thickening  at  regular  intervals  of  the  cuticular  lining. 
These  rods  are  bent  outward,  their  curvature  maintaining  the  flare  of  the 
rim  of  the  sucker.  Distally  they  terminate  just  inside  the  rim  of  the  cup 
and  basally  they  are  continuous  with  and  are  processes  from  a  band  of 
cuticula  which  passes  around  the  sucker  and  separates  the  external  and 
intermediate  portions.  In  toto  preparations  this  band  appears  to  be 
divided  into  sections  that  are  almost  square,  each  with  a  circular  area  in 
the  center  that  increases  and  decreases  in  size  as  the  focus  is  changed. 


3C11  NORTH  AMERICAN  POLYSTOMIDAE—STUNKARD  21 

Sections  show  that  the  euticular  lining  of  the  sucker  is  folded  outward 
against  the  convex  wall  with  which  it  is  fused,  thus  interrupting  the  con- 
tinuity of  the  fibrous  wall  (Fig.  35).  The  two  sides  of  this  invaginated 
euticular  sac  or  ring  are  fused  at  regular  intervals,  leaving  small  pockets 
alternating  with  the  places  of  fusion.  These  small  openings  in  the  euti- 
cular band  are  conspicuous  by  reason  of  their  different  refractive  index 
and  show  very  plainly  with  a  dark  field  illumination  as  the  square  or 
rectangular  sections  with  the  circular  areas  in  the  center  (Fig.  34). 
There  is  apparently  no  relation  between  the  number  of  these  sections  in 
the  euticular  band  and  the  number  of  euticular  thickenings  which  serve 
as  supports  of  the  external  section. 

The  middle  section  of  the  sucker  extends  basally  from  the  previously 
described  euticular  band  to  a  somewhat  similar  evagination  of  the  euti- 
cular lining  into  the  wall  of  the  sucker,  but  this  evagination  does  not  ex- 
tend to  the  external  euticular  covering  of  the  sucker  and  only  partially 
divides  the  fibrous  wall.  This  middle  or  intermediate  portion  of  the 
sucker  is  supported  by  thickenings  of  the  euticular  lining,  processes  that 
extend  peripherally  from  the  euticular  band  which  passes  around  the 
sucker  at  its  base.  These  supporting  ridges  are  not  arranged  at  regular 
intervals  and  they  are  much  fewer  in  number  than  the  euticular  rods 
which  support  the  external  section.  They  are  often  branched,  tho  not 
more  than  a  single  bifurcation  was  observed. 

The  basal  portion  of  the  sucker  is  circular,  similar  in  structure  to  the 
portions  previously  described ;  it  has  internal  and  external  limiting  mem- 
branes with  fibers  extending  between.  At  its  center  the  euticular  and 
fibrous  wall  is  interrupted  and  there  is  the  structure  described  by  John- 
son (1912)  as  the  connective  tissue  plug,  which  appears  as  a  central  disc 
or  button,  and  to  which  the  retractor  muscles  are  attached.  This  central 
disc  has  thickened  euticular  edges  and  bears  the  larval  booklet.  Figure 
44  illustrates  the  method  of  operation  of  the  suckers.  Muscles  are  at- 
tached to  the  external  wall  of  the  distal  and  intermediate  portions  of  the 
sucker  and  the  contraction  of  these  muscles  retracts  the  two  external 
zones,  with  the  accompanying  protrusion  of  the  basal  part.  Whether  the 
small  hooks  at  the  bases  of  the  suckers  are  functional  is  doubtful.  As 
previously  described,  the  euticular  supports  do  not  extend  quite  to  the 
external  margin  of  the  sucker,  leaving  a  soft  plastic  edge  which  can  be 
applied  all  the  way  around  even  on  an  irregular  surface.  "With  the  con- 
traction of  the  muscles  attached  to  the  basal  disc,  a  vacuum  is  produced 
and  forms  a  powerful  means  of  adhesion.  Since  the  walls  of  the  sucker 
are  not  contractile  and  the  suckers  vary  only  slightly  in  size  in  a  single 
species,  the  size  of  the  suckers  has  been  used  by  the  writer  as  a  character 
■  for  determining  specific  identity. 


22  ILLIXOIS  BIOLOGICAL  MOXOGRAPHS  [302 

A  euticular  framework  similar  to  that  present  in  Polystoma  was 
described  by  Wright  and  Macallum  for  the  suckers  of  Sphyranura  osleri. 
They  say:  "As  the  wall  of  the  sucker  is  itself  destitute  of  contractility, 
another  arrangement  exists  for  modifying  the  shape  of  the  cavity.  Its 
walls  is  really  divided  into  three  concentric  zones,  which  by  special  ex- 
trinsic muscles  can  be  worked  independently.  The  two  circular  lines 
which  separate  these  zones,  are  marked  by  an  infolding  of  the  investing 
membrane,  which  forms  a  sort  of  joint,  permitting  an  independent  move- 
ment of  the  zones." 

The  collection  of  Professor  Ward  contains  a  single  series  of  sections 
of  P.  integerrimum  from  Germany,  and  in  this  specimen  the  type  of 
skeletal  structure  just  described  is  absent.  Figure  45  shows  the  charac- 
ter of  the  suckers  in  this  form.  The  caudal  disc  typically  bears  eighteen 
hooks.  Sixteen  are  similar  in  size  and  shape,  arranged  as  follows:  six 
in  a  row  between  the  anterior  suckers,  one  situated  inside  each  sucker 
at  the  base,  and  four  between  the  two  posterior  suckers.  In  addition  to 
these  hooks  there  is  a  pair  of  great  hooks,  several  times  the  size  of  the 
small  hooks,  between  the  two  posterior  suckers.  The  shape  of  these  hooks 
and  their  arrangement  are  shown  in  Figures  37  to  43.  In  many  cases 
there  is  only  one  pair  of  the  small  hooks  between  the  caudal  suckers ;  in 
such  eases  in  addition  to  the  great  hooks  there  is  a  third  pair,  similar  in 
shape  to  the  great  hooks  and  intermediate  in  size  between  the  great  and 
small  hooks. 

The  sixteen  small  hooks  are  present  on  the  caudal  disc  of  the  larva 
before  the  suckers  are  formed  and  are  called  larval  booklets  by  Wille- 
mocs-Suhm  (1872),  but  Zeller  (1876)  says:  "Die  sechszehn  kleinen 
Hakchen  mit  ihren  Oesen,  welche  die  Haftscheibe  angehoren  und  welche 
bei  der  Polystomum  larva  so  ausserordentlich  deutlich  zu  erkennen  ist, 
sind  nicht,  wie  Willemoes-Suhm  meint,  nur  'Larvalorgane'.  Sie  werden 
nicht  abgeworfen,  sondern  sind  wie  ich  auf  das  bestimmeste  wiederholen 
muss,  bei  der  erwachsenen  Thiere  noeh  sammtlieh  vorhanden,  sehr 
beweglich  und  gewiss  nicht  ohne  Bedeutung  fiir  ein  festeres  Anheften." 
Jolm.ston  (1912)  in  the  description  of  P.  bulliense  says:  "Four  larval 
booklets  are  present  in  a  row  on  the  ventral  surface  near  the  posterior 
edge  of  the  disc  or  cotylophore.  I  have  been  able  to  find  no  trace  either 
in  the  living  worms  or  the  fixed  material,  of  tlie  larval  booklets  which 
P.  integerrimum  and  other  species  bear  near  the  anterior  edge  of  the 
disc.  There  is  a  small  anchor  shaped  liook  in  the  base  of  each  sucker. 
All  these  hooks  either  disappear  as  the  animal  increases  with  age,  or  very 
readily  become  detached.  In  only  one  out  of  sixteen  specimens  have  the 
whole  four  posterior  booklets  been  present ;  and  in  only  two  others  were 
any  booklets  at  all  to  be  seen.  In  all  other  specimens  no  booklets  could 
be  made  out." 


303]  XORTH  AMERICAN  POLYSTOMIDAE—STUNKARD  23 

lu  my  own  material  I  find  that  the  larval  hooklets  are  invariably 
present  in  the  bases  of  the  suckers,  but  of  the  other  larval  hooklets,  us- 
ually several  are  absent  and  often  those  present  are  so  arranged  that  it  is 
difficult  to  see  how  they  could  function  in  attachment.  Those  at  the  an- 
terior edge  of  the  caudal  disc  are  seldom  regularly  arranged,  and  in 
many  cases  (Figs.  37  to  43)  are  in  such  irregular  and  unusual  positions 
with  reference  to  each  other  that  the  use  of  one  would  interfere  with  the 
action  of  the  others. 

The  great  hooks  are  invariably  present  in  the  species  in  which  the 
caudal  disc  is  cordiform  in  shape,  i.  e.,  where  the  two  anterior  suckers  are 
separated  by  a  distance  exceeding  that  between  the  two  posterior  suckers. 
In  the  species  P.  alluaudi  and  P.  orbiculare  the  disc  is  circular  and  the 
great  hooks  are  absent.  Usually  the  cordiform  disc  is  wider  and  the  cir- 
cular disc  is  narrower  than  the  body.  At  first  it  seemed  possible  to 
separate  the  genus  into  two  subgenera,  one  in  which  the  disc  is  circular 
and  the  great  hooks  are  absent  and  another  with  a  cordiform  disc  and 
great  hooks  present,  but  there  seems  to  be  no  such  clear  line  of  separation. 
In  P.  arbiculare  a  large  number  of  ehitinous  spicules  are  present  on  the 
disc,  some  between  the  suckers  and  the  others  in  the  central  area  of  the 
disc.  In  P.  opacum  the  disc  is  intermediate  in  shape ;  it  is  difficult  to 
determine  whether  it  is  circular  or  cordiform,  and  the  great  hooks  are 
present  altho  they  are  not  more  than  half  the  size  of  those  in  other  species 
(Fig.  40).  In  P.  hassalli  the  disc  at  times  may  be  circular  and  the  great 
hooks  are  strongly  developed  (Fig.  31). 

Body  Covering. — The  body  is  covered  with  a  non-cellular,  unarmed 
cuticula,  which  is  turned  in  at  the  external  openings  of  the  various  sys- 
tems. It  does  not  have  a  uniform  appearance  but  is  traversed  by  lines 
which  extend  perpendicular  to  the  surface  of  the  body. 

Musculature. — The  musculature  consists  of  the  dermo-museular  sac, 
the  muscles  of  the  adhesive  apparatus,  and  dorso-ventral  strands  with 
much-branched  fibers  which  traverse  the  body  at  irregular  intervals.  The 
muscles  of  the  body  wall  consist  of  an  external  circular  layer,  an  interme- 
diate layer  of  diagonal  fibers,  and  inside  the  latter,  bundles  of  longitud- 
inal fibers.  In  all  the  species  studied,  the  inner  longitudinal  fibers  are 
more  strongly  developed  than  either  of  the  other  layers.  Stieda  (1870) 
in  P.  integerrimum  did  not  distinguish  between  the  two  external  muscle 
layers  and  described  only  two  layers  of  muscles,  an  outer  layer  of  an- 
nular fibers,  some  of  which  were  not  exactly  circular  and  crossed  each 
other,  and  an  inner  layer  of  longitudinal  fibers.  Zeller  (1876)  was  in 
error  when  he  described  the  diagonal  fibers  as  inside  the  longitudinal 
layer  in  P.  integerrimum.  The  arrangement  of  the  muscles  of  the  body 
wall  in  Polystoma  is  the  usual  condition  in  the  Heterocotylea,  and  a 


24  ILLIXOIS  BIOLOGICAL  MOKOGRAPHS  [304 

similar  arrangement  has  been  described  in  Calicotyle,  Axine,  Nitzschia, 
Tristomum,  Octobothrium,  Temnocephala,  Microcotyle,  Octocotyle,  and 
Monocotyle.  In  Diclidophora  Goto  (1894)  described  an  additional  layer 
of  longitudinal  fibers  between  the  circular  and  diagonal  layers.  He  states 
that  in  Onchocotyle  and  Hexacotyle  the  circular  fibers  seem  to  be  en- 
tirely lacking.  In  the  genus  Polystoma  there  are  strong  sets  of  longitudinal 
fibers  near  the  median  line  on  the  ventral  side  of  the  body.  They  could 
be  traced  anteriad  only  to  the  testis.  Posteriad  they  pass  into  the  caudal 
disc  and  together  with  fibers  from  the  body  wall  are  inserted  on  the  sides 
and  in  the  bases  of  the  bothria.  Muscle  strands  from  both  sides  of  the 
body  pass  to  each  of  the  suckers  (Fig.  29)  and  smaller  groups  of  fibers 
from  each  sucker  to  each  of  the  others.  In  addition  to  the  dorso-veutral 
muscles  which  extend  between  various  points  of  the  body  wall,  there  are 
other  fibers  from  the  body  wall  to  the  internal  organs. 

Mesenchyma. — The  mesenchymal  tissue  of  the  body  does  not  sliow 
a  differentiation  into  ectoparenchyma  and  endoparenchyma  as  described 
by  Brandes  (1892)  and  other  writers;  it  is  not  of  a  uniform  character, 
but  presents  differences  in  appearance  at  different  points  in  the  same 
specimen.  It  may  take  the  form  of  compact  cellular  tissue,  or  of  vacuo- 
lated cells,  or  there  may  be  large  vacuoles  apparently  between  cells,  or 
the  cellular  structure  may  be  entirely  lacking,  there  being  only  a  reticu- 
lum of  fibrous  tissue.  The  parenchyma  is  traversed  by  many  muscle 
strands,  and  the  dorsal  and  lateral  regions  are  occupied  by  the  enormous- 
ly developed  vitellaria  (Figs.  19,  23). 

Alimentary  System. — The  digestive  apparatus  consists  of  a  terminal 
anterior  or  oral  sucker,  a  pharynx,  a  short  esophagus  and  a  bifurcate  in- 
testine. The  oral  sucker  (Fig.  6)  is  not  fully  homologous  with  that  of 
the  distomes.  There  is  no  external  limiting  membrane,  branched  muscle 
fibers  passing  from  the  inside  lining  of  the  sucker  to  the  body  wall. 
Posteriorly  it  is  limited  and  separated  from  the  body  parenchyma  by 
special  strands  of  fibers  which  pass  from  the  body  wall  to  the  wall  of  the 
digestive  tube  and  are  attached  there  just  anterior  to  the  pharynx.  A 
contraction  of  these  fibers  causes  the  constriction  between  the  anterior 
sucker  and  the  body  parenehj^ma  which  is  sometimes  seen.  Longitudinal 
muscle  fibers  from  the  body  parenchyma  penetrate  this  posterior  boun- 
dry  of  the  anterior  sucker  and  pass  to  the  wall  of  the  sucker.  Annular 
muscles,  situated  just  inside  the  cuticular  lining,  pass  around  the  sucker 
from  side  to  side.  Situated  among  the  muscle  fibers  there  are  large 
secretory  cells.  Johnston  described  the  structure  as  a  weakly  developed 
or  incipient  oraj  sucker.  The  anterior  sucker,  pharynx,  and  esophagus 
are  lined  with  cuticula  continuous  with  that  of  the  external  surface  of 
the  body. 

/ 


I 

/ 


305]  NORTH  AMERICAN  POLYSTOMIDAE—STUNKARD  25 

The  pharynx  is  approximately  spherical,  altho  various  states  of  eon- 
traction  influence  its  shape  to  some  extent.  It  does  not  lie  directly  in  the 
long  axis  of  the  body  but  obliquely,  the  lumen  extending  from  the  some- 
what ventral  anterior  opening  from  the  oral  sucker  to  a  more  dorsal  pos- 
terior opening  into  the  esophagus  or  intestine.  In  certain  species  it  is 
composed  of  two  portions,  (Figs.  6,  33)  tho  both  are  enclosed  in  the  same 
external  capsule.  In  the  anterior  portion  there  are  many  strong  annular 
fibers  and  this  part  probably  acts  as  a  sphincter,  altho  there  are  also 
radial  fibers  which  extend  from  the  external  limiting  membrane  to  the 
cuticula  of  the  lumen.  In  the  posterior  part  the  annular  fibers  are  con- 
fined almost  entirely  to  the  external  region  and  a  small  central  zone 
(Fig.  25).  The  muscle  fibers  are  branched  and  non-nucleated.  Scattered 
among  the  fibers  in  the  posterior  part  there  are  large  nuclei,  each  with  a 
deeply  staining  nucleolus  and  surrounded  by  a  granvilar  or  flaky  ai-ea 
that  is  continued  by  a  fine  duct  traceable  by  the  presence  of  the  same 
granular  substance  and  leading  to  the  lumen  of  the  pharynx.  Goto 
described  somewhat  similar  nuclei  in  the  pharynx  of  Diclidophora  and 
regards  them  as  remnants  of  the  cells  that  have  produced  the  muscle 
fibers.  The  writer  is  inclined  to  the  view  that  in  Polystoma  the  granular 
substance  is  a  secretion.  No  extra-esophageal  glands  were  obsers'ed,  but 
that  the  secretion  of  the  pharyngeal  cells  is  salivary  was  not  demon- 
strated. 

A  short  esophagus  may  be  present  in  certain  species  (Fig.  6)  but  in 
most  cases  the  pharynx  appears  to  open  directly  into  the  intestine  at  the 
juncture  of  the  right  and  left  ceca.  There  maj'  be  a  short  median  or 
paired  lateral  pockets  of  the  intestine  extending  anteriad  from  the  junc- 
tion of  the  ceca. 

There  is  wide  variation  in  the  type  of  the  intestinal  diverticula.  In 
P.  integerrimum  the  ceca  are  much  branched  and  these  branches  ramify 
thru  the  body  and  the  caudal  disc  (Fig.  45).  In  P.  alluaudi  the  ceca  oc- 
cupy the  same  location  but  are  merely  lobed  and  have  no  secondary 
branches,  tho  they  are  united  posteriorly.  In  P.  bulliense,  according  to 
Johnston,  "a  diverticulum  from  the  buccal  cavity  runs  backwards,  ven- 
tral to  the  pharynx,  and  for  a  distance  equal  to  its  length  forming  a  me- 
dian unpaired  buccal  pocket."  In  all  other  known  species  there  is  a 
simple  bifurcate  intestine,  the  ceca  terminating  just  anterior  to  the  caudal 
disc.  In  two  specimens  of  P.  hassalli,  however,  the  ceca  are  connected 
posteriorly;  in  one  of  them  the  ends  of  the  ceca  are  continuous  and  in 
the  other  there  is  a  connection  some  distance  anterior  to  the  ends  of  the 
ceca  (Fig.  30).  The  walls  of  the  diverticula  are  composed  of  a  delicate 
fibro-membranous  tissue  upon  which  rests  the  digestive  epithelium.  The 
epithelial  layer  consists  of  columnar  cells  whose  nuclei  lie  near  the  fibro- 


26  ILLINOIS  BIOLOGICAL  MOSOGRAPHS  [306 

membranous  sheet  and  which  have  large,  rounded,  often  vacuolated  bodies 
extending  irregularly  into  the  canal.  The  protoplasm  of  the  cells  ia 
granular. 

Excretory  System. — In  this  family  as  in  all  Heterocotylea,  there  are 
two  excretory  pores,  situated  on  the  dorsal  surface  about  midway  between 
the  median  line  of  the  body  and  the  lateral  edge  of  the  worm,  near  the 
level  of  the  caudal  margin  of  the  pharjTix  (Fig.  27,  33).  These  open 
from  vesicular  expansions,  which  when  filled  are  almost  spherical  and 
when  empty  have  folded  walls.  The  descending  collecting  duct  originates 
in  the  region  of  the  pharj-nx  from  the  fusion  of  smaller  ducts  and  passes 
posteriad  to  the  region  of  the  caudal  disc  where  it  turns  cephalad  and 
continues  as  the  ascending  collecting  duct  to  open  into  the  excretory 
vesicle.  Both  the  descending  and  ascending  ducts  receive  smaller 
branches  at  irregular  intervals;  at  the  caudal  end  of  the  body  a  canal 
joins  the  tubes  of  the  two  sides  and  a  similar  connection  exists  between 
the  descending  ducts  just  anterior  to  the  pharynx.  From  this  anterior 
communicating  canal  a  branch  enters  the  anterior  sucker  near  the  median 
line.  The  excretory  vesicles  are  lined  with  a  thin  layer  of  cuticula  con- 
tinuous with  that  of  the  external  surface  of  the  body  and  the  collecting 
ducts  and  accessory  branches  have  a  fibro-membranous  wall  in  which 
nuclei  are  occasionally  embedded.  In  P.  integerrimitm,  Zeller  described 
many  connections  of  the  collecting  ducts  of  the  two  sides  thru  anastomoes 
of  their  smaller  branches.  He  also  described  cilia  on  the  walls  of  the  col- 
lecting ducts.  Looss  (1885)  described  the  excretory  system  of  P.  ocella- 
tiim.  He  says  the  collecting  ducts  are  not  ciliated  throuout,  but  only  in 
occasional  areas,  and  describes  cilia  in  the  capillaries.  These  capillaries 
are  long  and  at  the  distal  end  are  very  much  coiled.  In  this  coiled  part 
the  capillary  is  divided  so  that  two  flame  cells  discharge  into  each  coil 
and  are  emptied  by  a  single  capillarj-.  The  caliber  of  the  excretory  ves- 
sels is  verj'  minute,  and  altho  varying  somewhat  as  a  result  of  distention, 
lacunar  expansions  were  not  observed.  Because  of  the  limited  amount  of 
material,  much  of  which  was  received  in  a  preserved  condition,  no  at- 
tempt was  made  to  trace  the  exeretorj-  system  in  living  worms  of  this 
family.  The  vitellaria  completely  obscure  the  excretory  ducts  in  toto 
preparations.  The  secondary  ducts  are  so  small  and  so  often  collapsed 
that  it  is  impossible  to  follow  their  continuity  with  certainty  in  sections. 

Nervous  System. — The  morphology  of  the  nervous  s3-stem  of  P. 
integerrimitm  was  described  in  detail  by  Andre  (1910).  He  described  a 
supra-esophageal  brain  from  which  three  pairs  of  nerves  pass  anteriad 
and  three  pairs  posteriad.  In  another  paper  (1910a)  he  gave  a  detailed 
description  of  the  eyes  of  P.  integerrimum.  In  the  present  work  no 
special  study  of  the  nervous  system  was  made  and  no  new  facts  were 
adduced. 


307]  NORTH  AMERICAN  POLYSTOMIDAE—STUNKARD  27 

Male  Reproductive  System. — The  testis  is  a  much  branched  structure 
in  P.  kachugae;  in  P.  integerrimum  it  is  lobed,  and  in  the  other  known 
species  it  is  oval  or  spherical.  It  is  situated  near  or  slightly  anterior  to 
the  middle  of  the  body.  A  duct  designated  an  internal  vas  deferens  was 
described  in  P.  integerrimum  by  Zeller,  but  Ijima  (1884)  traced  the  true 
relations  of  this  tube  and  showed  that  it  passes  from  the  ootype  to  the  in- 
testine. Goto  (1894)  proposed  the  name  canalis  genito-intestinalis  for 
this  structure  which  is  discussed  in  a  later  section.  The  vas  deferens 
arises  from  the  dorso-cephalic  margin  of  the  testis  and  passes  dorsad  and 
anteriad.  It  extends  dorsal  to  the  ootype,  between  the  dorsal  margins  of 
the  ovary  and  uterus  to  the  level  of  the  genital  pore  where  it  turns  ven- 
trad  and  enlarges  to  form  the  seminal  vesicle  (Fig.  13).  From  the  semi- 
nal vesicle  a  duct  passes  thru  the  cirrus  sac,  opening  into  the  genital 
atrium  (Fig.  26).  The  vas  deferens  is  small  and  has  a  fibro-membran- 
ous  wall,  and  the  seminal  vesicle  has  a  lining  of  columnar  epithelium. 
The  cirrus  sac  is  composed  of  an  external  muscular  waU  enclosing  a  mass 
of  parenehymous  tissue  which  surrounds  the  ejaculatory  duct.  This  sac 
is  very  small  in  P.  integerrimum  and  P.  hassalli.  Ventrally  it  opens  into 
a  common  genital  atrium  (Fig.  26).  The  ejaculatory  duct  terminates  in 
the  genital  papilla,  which  when  retracted  is  surrounded  by  a  deep  depres- 
sion. In  the  musculature  between  this  depression  and  the  wall  of  the 
cirrus  sac  are  embedded  the  roots  of  the  genital  hooks.  "When  the  hooks 
are  retracted  there  is  a  shallow  depression  between  them  and  the  wall  of 
the  sac.  With  the  contraction  of  the  wall  of  the  cirrus  sac  the  genital 
papilla  and  the  circle  of  genital  hooks  are  extruded  thru  the  pore.  In 
most  of  the  species  the  hooks  are  sickle  shaped  with  the  points  project- 
ing outward,  and  with  muscles  attached  to  the  outside  of  the  hook  at  the 
juncture  of  the  root  and  shank.  These  muscles  undoubtedly  serve  as  a 
fulcrum,  and  the  extrusion  of  the  papilla  rolls  the  hooks  outward  bury- 
ing their  points  in  the  eutieula  lining  the  wall  of  the  vagina  of  the  copu- 
lating worm  (Fig.  24).  In  P.  alluaudi  Beauehamp  described  three 
genital  hooks,  P.  integerrimum  has  eight,  and  other  species  sixteen, 
thirty-two,  and  forty.  In  P.  hassalli  the  genital  hooks  are  small,  straight 
and  have  a  wing  like  process  at  the  middle. 

Zeller  described  a  prostate  gland  in  P.  integerrimum,  consisting  of 
masses  of  large  cells  situated  around  the  cirrus,  and  traced  ducts  from 
these  cells  to  the  lumen  of  the  ejaculatory  duct.  Johnston  in  P.  bulliense 
says,  "Two  laterally  placed,  small  groups  of  gland  cells  represent  the 
prostate."  The  statement  of  Zeller  that  a  gland  is  present  around  the 
cirrus  of  P.  integerrimum  is  certainly  correct.  In  the  species  described 
in  this  paper,  a  similar  gland  is  present  in  the  parenchyma  around  the 
genital  sinus.    The  cells  (Fig.  12)  are  globular  or  pyriform,  stain  deeply 


28  ILLINOIS  BIOLOGICAL  MONOGRAPHS  [308 

and  possess  a  distinct  nucleus  and  nucleolus.  Their  ducts  could  not  be 
traced  to  the  ejaculatory  duct  but  in  many  cases  appear  to  lead  to  the 
body  wall  near  the  margin  of  the  genital  sinus.  In  P.  orhiculare,  P. 
opacum  and  P.  megacotyle  the  cirrus  sac  is  large  and  many  nuclei  are 
present  around  the  ejaculatory  duct  in  the  dorsal  part  of  the  sac.  These 
nuclei  are  large,  with  distinct  nucleoli,  and  are  surrounded  by  a  deeply 
staining  area  of  granular  or  flaky  substance,  but  no  cell  boundries  could 
be  made  out. 

Female  Reproductive  System. — In  all  known  species  but  one,  the 
ovary  is  oval  or  comma  shaped.  In  P.  kachugae  it  is  described  by  Stew- 
art as  a  "curved  sausage-shaped  organ,  the  curve  forming  all  but  a  com- 
plete circle.  The  fundus  is  somewhat  bulbous."  This  structure  is 
usually  not  more  than  one  half  the  size  of  the  testis,  is  situated  a  short 
distance  anterior  to  that  organ,  and  in  a  given  species  may  lie  on  either 
side  of  the  body.  In  all  the  species  studied  by  the  writer  it  is  comma 
shaped,  the  larger  part  is  ventral,  anterior,  and  lateral,  and  terminal 
region  is  dorsal,  posterior,  and  mesal.  The  ova  are  formed  in  the  large 
part  and  the  ovary  is  divided  into  zones  of  growth,  ova  of  increasing  size 
being  present  in  each  succeeding  zone  (Fig.  23). 

In  the  species  described  in  this  paper  the  viteUaria  consist  of  masses 
of  foUicles  occupying  the  dorsal  and  lateral  regions  of  the  body.  Each 
follicle  consists  of  several  cells  which  may  vary  much  in  appearance ;  the 
difference  is  due  to  the  phase  of  secretory  activity  of  the  cells.  In  the 
peripheral  part  of  the  gland  the  ceUs  are  usually  small,  with  granular  or 
flaky  protoplasm,  a  distinct  nucleus  and  nucleolus;  whereas  those  more 
centrally  located  may  be  two  or  three  times  their  size,  the  extra-nuclear 
area  being  either  vacuolated  or  filled  with  droplets  of  a  yellow  substance 
(Figs.  19,  20).  In  some  cells  the  secretory  droplets  are  scattered  uni- 
formly thruout  the  cell.  The  presence  of  the  material  in  the  cells  often 
renders  the  body  so  opaque  that  the  diverticula  can  not  be  seen.  The 
glandular  secretion  is  apparently  identical  with  that  which  forms  the  shell 
of  the  egg,  and  this  observation  further  confirms  the  statement  of  Gold- 
schmidt  (1909)  that  the  so-called  vitellaria  secrete  the  shell  of  the  egg. 
Small  ducts  from  the  follicles  (Fig.  11)  unite  and  discharge  into  longi- 
tudinal collecting  ducts.  These  extend  along  the  sides  of  the  body,  later- 
al to  the  ceca  and  dorsal  to  the  excretory  tubules ;  on  either  side  of  the 
body  there  is  an  anterior  and  a  posterior  branch  which  unite  just  behind 
the  level  of  the  ovary  and  the  common  duct  discharges  into  the  external 
end  of  the  vitello-vaginal  canal.  In  P.  hulliense,  Johnston  reports :  ' '  The 
lateral  vaginal  swellings  are  formed  by  a  large  number  of  papillae,  per- 
forated by  fine  canals,  which  after  a  very  short  course,  open  into  a  fairly 
wide  sperm  reservoir,  situated  one  on  either  side,  just  under  the  swell- 


309]  NORTH  AMERICAN  POLYSTOMIDAE—STUNKARD  29 

ings.  From  these  reservoirs,  a  wide  vaginal  txibe  on  either  side  runs 
backwards  and  inwards,  to  open  into  the  anterior  lateral  yolk  duet." 
A  similar  condition  is  described  and  figured  by  Zeller  for  P.  integerri- 
mum.  In  all  other  species  in  which  the  structure  has  been  described,  the 
vaginae  are  open  funnels  leading  mediad  and  dorsad  from  their  openings 
on  the  ventro-lateral  surface  of  the  body,  and  uniting  just  below  the  in- 
testine with  the  common  vitelline  ducts  to  form  the  vitello- vaginal  canals. 
The  cuticular  lining  of  the  vaginae  is  very  thick  and  in  the  parenchyma 
around  the  vaginae  there  are  large  cells  of  secretory  type  (Fig.  24).  The 
vitello-vaginal  canals  lead  medially  and  unite,  either  forming  a  duet 
which  discharges  into  the  ootype  (Fig.  32)  or  opening  separately  into 
the  ootype  (Figs.  3,  16,  24). 

From  the  ovary  the  oviduct  passes  posteriad  and  ventrad,  opening 
into  the  ootype.  Immediately  anterior  and  dorsal  to  the  opening  of  the 
oviduct,  there  branches  from  the  ootype  a  small  tube  which  after  a  some- 
what twisted  double  loop  opens  into  the  intestine  of  the  side  in  which  the 
ovary  is  situated.  This  genito-intestinal  canal  has  been  the  source  of 
much  controversy  and  its  presence  or  absence  is  the  diagnostic  feature  of 
Odhner's  two  groups  of  monogenetic  trematodes.  Mehlis'  gland,  the  shell 
gland  of  earlier  authors,  is  never  largely  developed  and  is  difficult  to 
find  in  some  specimens  where  it  is  represented  by  a  few  nuclei  in  the 
parenchyma  around  the  ootype.  Zeller  for  P.  integerrimum  and  John- 
ston for  P.  iulliense  described  prominent  "shell  glands",  and  Stewart 
for  P.  kachugae  described  ' '  a  group  of  glandular  cells  found  at  the  same 
transverse  level  as  the  ovary,  but  on  the  opposite  side  of  the  midline. 
They  appear  to  be  connected  with  the  corresponding  vagina,  but  their 
function  is  obscure."  Since  they  are  in  the  precise  location  of  the 
Mehlis'  gland,  one  is  led  to  suspect  that  Stewart  was  confused  in  regard 
to  the  connections  and  relations  of  this  group  of  ceUs,  altho  in  in- 
dividuals of  other  species  studied  by  the  writer,  there  are  groups  of 
large  glandular  cells  in  the  parenchyma  surrounding  each  vagina. 

The  ootype  is  continued  by  a  tube  which  passes  anteriad  on  the  op- 
posite side  from  the  ovary,  and  which  leads  to  the  uterus.  Previous 
writers  have  called  this  tube  the  oviduct  and  Johnston  (1912)  says, 
"From  the  ootype,  the  oviduct  runs  forward  to  a  point  in  front  of  the 
ovary,  whence  it  bends  sharply  backwards  and  runs  in  a  straight  course 
close  to  the  ventral  surface,  almost  to  the  level  of  the  cotylophore,  where 
it  opens  into  the  wide  uterus. ' '  The  use  of  the  term  oviduct  for  the  tube 
leading  from  the  ootype  to  the  uterus  is  confusing  and  objectionable. 
Looss  (1899)  says,  "Der  Theil  des  weibMchen  Leitungswegen,  der  den 
Keimstock  mit  dem  ootjrp  verbindet,  ist  der  oviduct  oder  Keimgang," 
and  this  terminology  is  found  in  general  use  thruout  the  literature.  In  a 
large  number  of  trematode  genera  the  ootype  opens  directly  into  the 


30  ILLINOIS  BIOLOGICAL  MONOGRAPHS  [310 

uterus.  In  the  Polystomidae  however,  there  is  a  definite  specialized  tube 
leading  from  the  ootype  to  the  uterus.  This  duct  is  not  homologous  with 
the  oviduct,  it  is  separated  from  that  duct  by  the  ootype,  and  further, 
in  the  specimens  examined  by  the  MTiter  the  histological  character  of  the 
two  are  not  precisely  the  same.  The  epithelial  lining  of  the  oviduct  is  of 
the  flattened  type,  and  that  of  the  second  duct  more  columnar.  Such  a 
duct  is  present  in  many  cestode  genera  and  is  called  the  uterine  duct. 
The  same  name  is  proposed  for  the  tube  leading  from  the  ootype  to  the 
uterus  in  the  Polystomidae,  altho  with  the  understanding  that  its  use  is 
independent  of  the  question  of  homologies  of  the  female  ducts  in  trema- 
todes  and  cestodes. 

In  P.  hulliense  the  uterine  duct  opens  into  the  uterus  not  at  the  end 
but  on  the  side,  and  there  is  a  posterior  uterine  pocket.  The  uterus  ex- 
tends as  a  wide  elongated  sac  from  the  extreme  posterior  end  of  the  body 
to  the  common  genital  sinus.  In  P.  alluaudi  the  intracecal  area  is  occu- 
pied by  the  uterus  and  eggs  are  present  almost  as  far  posteriad  as  the 
caudal  union  of  the  ceca.  In  P.  integerrimum  there  is  a  long  uterus 
which  extends  in  many  loops  anterior  to  the  ootype,  and  contains  a  large 
number  of  eggs.  In  all  other  known  forms,  the  uterus  is  situated  at  the 
level  of  the  ovary  on  the  opposite  side  of  the  body,  and  contains  a  single 
large  egg  or  embryo.  Zeller  (1876)  described  a  similar  condition  for 
the  ectoparasitie  form  of  P.  integerrimum.  Figure  14  shows  a  verj-  early 
embyro  of  P.  orhiculare  and  Figure  23  a  much  later  stage  of  development 
in  P.  megacotyle.  No  shell  is  present  in  the  former  case,  altho  it  may 
have  been  lost  in  sectioning.  There  must  be  some  provision  for  the 
growth  of  the  embryo  and  the  shell  can  not  be  rigid  during  the  uterine 
period.  Where  the  oviduct  arises  from  the  ovary,  at  its  union  with  the 
ootype,  and  at  either  end  of  the  uterine  expansion  sphincter  muscles  pro- 
duce short  contracted  portions  of  the  tube.  In  all  the  species  studied  by 
the  writer,  with  the  exception  of  the  vitelline  tubules,  all  ducts  of  the 
female  system  have  a  fibro-membranous  wall  and  an  epithelial  lining, 
which  in  the  ootype,  uterine  duct,  and  uterus  consists  of  tall  columnar 
cells  with  distinct  boundries  and  single  nuclei.  Describing  the  epithelial 
ceUs  lining  the  ootype  in  certain  other  monogenetic  forms  Goto  (1894) 
says  that  because  of  their  appearance  and  reaction  to  stains  he  strongly 
suspects  theii'  glandular  nature,  but  since  a  shell  gland  is  present  he  can 
not  understand  their  function.  In  certain  species  of  Polystoma  Mehlis' 
gland  is  much  reduced  or  absent,  and  in  these  forms  the  cells  of  the 
epithelial  lining  of  the  ootype  appear  to  be  secretive  (Figs.  8,  9).  This 
agrees  with  the  present  conception  that  the  vitellaria  secrete  the  shell 
substance  and  Mehlis'  gland  the  fluid  in  which  the  eggs  are  suspended. 

The  genital  pore  is  situated  on  the  ventral  surface  in  the  median 


311]  NORTH  AMERICAN  POLYSTOMIDAE—STUNKARD  31 

line,  just  posterior  to  the  bifurcation  of  the  digestive  tract.  It  opens 
from  a  common  genital  sinus  (Figs.  13,  26)  into  which  the  uterus  dis- 
charges and  thru  which  the  cirrus  is  extruded.  The  opening  from  the 
uterus  into  the  genital  sinus  is  posterior  and  ventral,  while  the  cirrus  sac 
opens  into  the  dorsal  part  of  the  atrium. 

When  the  two  specimens  of  P.  opacum  from  Trionyx  ferox  were 
placed  in  a  watch  glass,  they  soon  came  in  contact  and  immediately 
started  copulation,  the  cirrus  of  each  worm  was  inserted  in  the  right 
vagina  of  the  other,  and  the  two  worms  attached  to  each  other,  both  with 
the  anterior  suckers  and  those  of  the  caudal  disc  that  could  be  brought  in 
position  for  adhesion.  Attempts  to  separate  the  worms  failed,  so  an 
effort  was  made  to  fix  them  in  the  copulating  condition,  but  they  separated 
on  the  application  of  the  killing  fluid.  This  explains  the  statement  of 
Johnston:  "On  one  side  only,  in  the  specimens  sectioned,  was  the 
vaginal  tube  filled  with  sperms;  that  on  the  other  side  was  empty." 
Benham  (1901)  and  Mac  Galium  (1913)  state  that  copulation  in  poly- 
stomes  has  been  observed  only  by  Zeller. 

POLTSTOMA  ORBICULARE  Stunkard  1916 
[Figures  1  to  14] 

The  material  of  this  species  consists  of  six  specimens  from  the 
urinary  bladder  of  Pseudemys  scripta  from  Raleigh,  North  Carolina, 
one  specimen  from  the  urinary  bladder  of  Chrysemys  marginata  from 
Chicago,  Illinois,  and  two  specimens  from  the  urinary  bladder  of  Chry- 
semys marginata  from  Creston,  Iowa. 

The  body  is  an  elongate  oval,  slightly  more  pointed  anteriorly  than 
posteriorly,  and  in  two  of  the  specimens  with  slight  indentations  of  the 
body  walls  at  the  vaginae  and  at  the  posterior  margin  of  the  anterior 
sucker.  These  worms  (Fig.  1)  varied  in  length  from  2.7  to  3.75  mm. 
and  in  width  from  0.9  to  1.2  mm.  The  caudal  disc  is  circular,  0.8  to 
1.07  mm.  in  width,  and  bears  the  six  suckers  arranged  symmetrically 
in  a  circle.  The  suckers  are  approximately  0.3  mm.  in  diameter,  and 
are  separated  by  regular  equal  intervals.  No  hooks  could  be  found  on 
the  caudal  disc  with  the  exception  of  the  single  minute  larval  booklet 
in  the  base  of  each  sucker.  These  are  0.016  mm.  in  length  and  could  be 
seen  only  under  favorable  conditions. 

The  anterior  sucker  (Fig.  6)  is  0.25  to  0.27  mm.  in  length  and 
0.37  to  0.42  mm.  in  width.  It  opens  into  the  pharynx,  a  spherical  struc- 
ture 0.24  to  0.28  mm.  in  diameter.  There  is  a  short  esophagus  visible 
in  sagittal  sections  altho  it  is  not  distinguishable  in  toto  preparations. 
The  ceca  meet  anteriorly  in  a  wide  curve  and  extend  as  simple  tubes 


32  ILLINOIS  BIOLOGICAL  MONOGRAPHS  [312 

almost  to  the  posterior  end  of  the  body.  They  have  no  branches  and 
terminate  blindly.     In  caliber  they  vary  from  0.04  to  0.116  mm. 

The  testis  is  spherical  or  oval,  usually  slightly  longer  than  broad, 
and  measures  0.29  to  0.39  mm.  in  width  and  0.36  to  0.5  mm.  in  length. 
It  is  near  or  slightly  anterior  to  the  middle  of  the  body.  The  sperm 
duct  arises  at  its  anterior  margin  and,  lying  dorsal  to  the  ootype,  passes 
anteriad.  In  front  of  the  ovary  it  turns  ventrad  and  expands  into  the 
seminal  vesicle.  At  the  outer  end  of  the  seminal  vesicle  the  duct  is 
encircled  by  a  sphincter  muscle,  and  then  known  as  the  ejaculatory 
duct  passes  thru  the  cirrus  sac  to  open  into  the  genital  atrium  (Figs. 
3,  13).  The  cirrus  sac  is  almost  spherical,  and  consists  of  an  external 
muscular  capsule  filled  with  parenchymatous  tissue  enclosing  a  central 
canal.  In  the  dorsal  part  of  the  sac  there  are  radial  muscles  passing 
from  the  wall  to  the  central  duct,  and  among  these  fibers  a  few  large 
nuclei.  More  ventrally  there  are  sets  of  muscles  developed  around  the 
central  duct  and  these  are  connected  to  the  wall  of  the  sac.  Externally 
the  central  canal  terminates  at  the  apex  of  a  papilla  which  is  separated 
by  a  deep  depression  from  the  muscular  ring  that  bears  the  hooks  of 
the  genital  coronet.  This  conical  muscular  ring  is  protrusible  and  is 
separated  from  the  wall  of  the  cirrus  sac  by  a  second  depression.  The 
invaginations  on  either  side  of  the  genital  coronet  allow  for  the  extru- 
sion of  the  coronet  of  hooks  with  the  genital  papiUa  on  the  contraction 
of  the  wall  of  the  cirrus  sac,  while  the  muscles  attached  to  the  central 
canal  and  the  muscular  ring  bearing  the  genital  hooks  serve  as  retract- 
ors. The  genital  coronet  consists  of  sixteen  hooks,  similar  in  size  and 
shape;  they  have  an  external  sickle-shaped  part  or  shank  which  turns 
outward  and  a  root  or  basal  part  of  about  the  same  length  embedded 
in  the  musculature  (Figs.  2,  13).  The  basal  part  is  straight  and  hollow 
and  the  internal  end  is  bifurcate.  It  bears  many  fine  cuticular  processes 
which  are  particularly  prominent  near  its  union  with  the  shank.  In  the 
body  parenchyma  around  the  terminal  part  of  the  cirrus  sac  there  are 
large  unicellular  glands  (Figs.  12,  13). 

The  ovary  is  lateral  and  may  be  situated  on  either  side  of  the  body. 
It  is  0.1  to  0.25  mm.  anterior  to  the  testis.  It  is  ovoid  in  shape,  ^vith 
the  larger  part  in  which  the  ova  are  being  formed  anterior  and  ventral, 
and  the  oviduct  arising  from  the  dorsal  posterior  region.  In  sections  it 
appears  to  be  marked  into  zones,  with  larger  and  fewer  cells  present  in 
each  succeeding  zone.  It  is  0.1  to  0.148  mm.  in  width,  0.14  to  0.185  mm. 
in  length  and  in  one  specimen  cut  in  cross  sections  0.175  mm.  in  depth. 
The  oviduct  arises  as  a  very  small  tube  and  immediately  expands  (Fig. 
3).  This  expanded  portion  extends  posteriad  and  ventrad  and  by  means 
of  a  short  constricted  tube  opens  into  the  ootype,  a  specialized  region 


313]  NORTH  AMERICAN  POLYSTOMIDAE—STUNKARD  33 

of  the  female  duct  where  the  vitello-vaginal  canals  are  received  and  the 
genito-intestinal  canal  is  given  off.  The  genito-intestinal  canal  twists 
in  a  double  loop  and  then  opens  into  the  intestine  of  the  side  upon 
which  the  ovary  is  located  (Fig.  10).  The  vaginae  are  ventro-lateral  in 
position  and  open  to  the  exterior  by  funnel  shaped  mouths.  The  vitel- 
laria  occupy  the  dorsal  and  lateral  regions  of  the  body;  they  extend 
anteriad  to  the  pharynx  and  posteriad  to  the  caudal  disc.  There  is  a 
Strand  of  follicles  across  the  dorsal  side  of  the  body  just  behind  the 
pharynx,  and  then  the  follicles  are  entirely  extracecal  in  the  field  ante- 
rior to  the  testis;  posterior  to  the  testis  the  vitellaria  overlie  the  ceca 
and  extend  to  the  center  altho  they  are  scanty  along  the  median  line. 
Ventrally  the  vitellaria  are  entirely  extracecal.  Collecting  duets  run 
longitudinally,  laterad  of  the  ceca ;  and  just  below  the  cecum  of  either 
side  the  common  vitelline  ducts  formed  by  the  union  of  the  anterior 
and  posterior  longitudinal  ducts  unite  with  the  internal  ends  of  the 
vaginae  to  form  the  vitello-vaginal  canals.  These  canals  open  directly 
into  the  ootype,  one  on  either  side,  and  are  thus  continuous,  forming  a 
canal  thru  the  body  from  side  to  side.  Mehlis'  gland  is  represented  by 
many  nuclei  which  lie  in  the  parenchyma  around  the  ootype  and  uterine 
duct.  This  latter  duct  passes  anteriad  and  laterad  on  the  opposite  side 
from  the  ovary ;  it  is  smaller  than  the  ootype  in  diameter  and  the  epithe- 
lial lining  is  lower.  After  a  slight  expansion  it  is  constricted  and  then 
opens  into  the  uterus.  The  uterus  contained  a  single  eg^  or  embryo. 
Figure  14  shows  a  morula-like  mass  of  cells  found  in  one  specimen;  in 
the  other  specimens  there  were  large  spherical  eggs,  each  enclosed  in  a 
yellow  shell.    They  vary  from  0.21  to  0.24  mm.  in  diameter. 

The  excretory  system  shows  no  departure  from  the  typical  form 
and  while  it  can  not  be  completely  followed  in  sections,  the  larger  ducts 
occupy  the  characteristic  positions.  The  descending  collecting  ducts 
arise  in  the  region  of  the  anterior  sucker  and  pass  posteriad,  lying  lat- 
eral and  ventral  to  the  ceca.  They  wind  back  and  forth  in  short  curves 
and  at  the  posterior  end  of  the  body  turn  anteriad  and  pass  in  the  same 
winding  course  to  the  excretory  vesicles.  Both  descending  and  ascend- 
ing ducts  receive  small  branches  at  irregular  intervals.  The  excretory 
pores  are  lateral  and  dorsal,  at  the  level  of  the  bifurcation  of  the 
intestine  (Fig.  7). 

This  species  agrees  with  P.  alluaudi  in  shape  of  caudal  disc  and 
absence  of  great  hooks,  but  differs  from  that  species  in  type  of  uterus, 
number  of  hooks  in  the  genital  coronet,  and  in  the  character  of  the 
intestinal  diverticula  and  testis.  P.  oriiculare  agrees  with  P.  hassalli 
in  the  number  of  genital  hooks,  but  the  hooks  are  different  in  size  and 
shape ;  P.  hassalli  has  the  great  hooks  of  the  caudal  disc  well  developed 


34  ILLINOIS  BIOLOGICAL  MONOGRAPHS  [314 

whereas  they  are  absent  in  this  species.  In  certain  particulars  P.  or- 
biculare  resembles  P.  opacum,  but  the  two  species  have  different  num- 
bers of  hooks  in  the  genital  coronets ;  they  differ  also  in  the  relative  size 
of  caudal  suckers.  The  great  hooks  of  the  caudal  disc  are  present  in 
P.  opacum.  The  two  species  differ  also  in  that  one  is  parasitic  in  the 
urinary  bladder  and  the  other  in  the  oral  cavity. 

POLYSTOMA  OPACUM  Stunkard  1916 
[Figures  15  to  21] 

Two  worms  of  this  species  were  obtained  from  the  esophagus  of  a 
single  specimen  of  Trionyx  ferox  from  Newton,  Texas,  and  another 
from  the  esophagus  of  Malacoclemmys  lesueurii  from  the  same  region. 
These  trematodes  were  the  same  color  as  the  lining  of  the  esophagus 
and  so  firmly  attached  that  they  were  removed  only  with  great  difficulty. 

The  worms  (Fig.  15)  measured  4,  3.75,  and  3.25  mm.  in  length  and 
1,  0.85  and  0.8  mm.  respectively  in  width.  The  body  has  an  elongate 
oval  outline,  is  flattened  dorso-ventraUy,  and  observed  in  living  condi- 
tion, shows  great  variations  in  shape.  In  an  extended  condition  it  nar- 
rows at  either  or  both  ends,  and  the  contracted  form  may  be  not  more 
than  half  the  length  when  extended,  and  broadly  oval  or  quadrate  in 
outline.  The  caudal  disc  is  slightly  wider  than  the  body  in  the  mounted 
specimens,  measuring  1.09  and  1.21  mm.  in  width  while  each  sucker  is 
approximately  0.4  mm.  in  diameter.  The  suckers  have  a  chitinous  skele- 
tal framework,  as  is  described  in  the  generic  discussion.  In  the  external 
meridinal  band  there  are  thirty-two  divisions,  which  number  corre- 
sponds to  the  number  of  hooks  in  the  genital  coronet.  The  suckers  are 
arranged  in  a  circle,  altho  the  anterior  pair  are  separated  by  a  distance 
slightly  exceeding  that  between  the  posterior  pair.  Between  tlie 
anterior  suckers  there  are  many  chitinous  spicules,  and  in  one  specimen 
two  of  the  larval  booklets.  Chitinous  spicules  are  present  on  the  sides 
of  aU  the  suckers  and  over  the  ventral  surface  of  the  disc.  Between  the 
posterior  suckers  there  are  three  pairs  of  hooks,  viz.  two  pairs  of  the 
small  larval  hooks  and  one  larger  pair,  but  the  great  hooks  are  relatively 
much  smaller  than  the  corresponding  hooks  in  other  species  in  which 
they  are  present  (Fig.  40).  The  larval  booklets  are  7  to  9/t  in  length 
and  the  great  hooks  are  75/*  in  length.  The  chitinous  spicules  present 
on  the  disc  have  no  definite  arrangement  and  their  points  may  stand 
in  any  direction;  the  three  larval  hooks  between  the  anterior  suckers 
of  one  specimen  have  no  definite  relative  position  and  their  hooks  point 
in  different  directions;  those  at  the  posterior  edge  of  the  disc  are  set 


315]  NORTH  AMERICAN  POLYSTOMIDAE—STUNKARD  3S 

in  a  row  at  more  or  less  regular  intervals  and  their  hooks  all  point 
backward. 

The  cuticular  covering  of  the  body  is  about  14/i  in  thickness,  and 
on  the  contraction  of  the  body  is  thrown  into  minute  folds  and  furrows. 

The  anterior  sucker  is  oval,  0.2  to  0.22  mm.  in  length  and  0.23  mm. 
in  width.  It  opens  into  the  pharynx  (Fig.  18),  a  spherical  structure 
.0.3  mm.  in  width.  There  is  a  broad  nerve  commissure  crossing  the  an- 
terior part  of  the  pharynx  which  contains  large  ganglion  cells.  From 
this  dorsal  commissure  a  nerve  passes  ventrad  on  either  side  of  the 
pharynx. 

The  digestive  tract  is  of  the  simple  triclad  type,  the  pharj-nx  is  fol- 
lowed by  a  short  esophagus,  0.17  mm.  in  length  in  the  sectioned  worm, 
and  the  diverticula  extend  as  simple  tubes  almost  to  the  posterior  end 
of  the  body.  They  are  about  0.15  mm.  in  diameter  and  terminate  blindly, 
dorsal  to  the  middle  pair  of  suckers  (Fig.  21).  The  ceca  are  lateral  but 
close  together,  separated  by  only  0.2  to  0.25  mm.  They  have  the  usual 
fibro-membranous  coat  and  epithelial  lining,  and  were  empty  in  the 
sectioned  individual. 

The  testis  is  spherical  or  slightly  longer  than  broad  in  well  extended 
specimens.  It  is  slightly  anterior  to  the  middle  of  the  body  and  is  com- 
posed of  a  large  number  of  lobes  or  strands  of  cells,  compacted  and 
enclosed  in  a  membranous  capsule.  Cells  with  the  chromatin  of  their 
nuclei  in  all  stages  of  division  and  mature  spermatozoa  were  observed 
in  sections.  The  sperm  duct  arises  at  the  anterior  dorsal  margin  of  the 
testis  and  curves  dorsad  and  eephalad.  Anterior  to  the  uterus  it  turns 
ventrad  and  expands  to  form  the  seminal  vesicle.  From  the  seminal 
vesicle  a  small  ejaculatory  duct  leads  through  the  cirrus  sac  and  opens 
into  the  common  genital  sinus. 

The  ovary  is  ovoid  or  comma  shaped,  situated  a  short  distance 
anterior  to  the  testis,  and  in  aU  three  specimens  is  located  on  the  left 
side  of  the  body ;  but  since  in  other  species  it  may  lie  on  either  side,  it 
is  probable  that  the  examination  of  a  larger  number  of  individuals 
would  show  specimens  with  the  ovary  on  the  right  side.  In  dorsal  view 
it  is  from  0.16  to  0.2  mm.  in  length  and  0.08  to  0.12  mm.  in  width,  while 
in  the  specimen  that  was  sectioned  it  is  0.08  mm.  in  width  and  0.3  mm. 
in  depth.  The  oviduct  arises  at  the  dorsal  posterior  margin  and  curves 
posteriad,  mediad,  and  ventrad  where  it  opens  into  the  ootype.  The 
vitello-vaginal  canals  open  separately  into  the  ootype,  just  ventral  to  the 
origin  of  the  genito-intestinal  canal.  The  latter  duct  passes  laterad, 
then  dorsad  and  anteriad,  turns  mediad  almost  to  the  median  line  of 
the  body,  then  dorsad  and  laterad,  and  opens  into  the  intestine  of  the 
side  in  which  the  ovary  is  located.    The  uterine  duct  passes  to  the  right 


36  ILU.XOIS  BIOLOGICAL  MOXOGRAPHS  [316 

sight  of  the  body,  then  dorsad  and  anteriad  where  it  opens  into  the 
uterus.  Mehlis'  gland  is  present  altho  not  well  developed,  and  the  cells 
are  scattered  along  the  uterine  duct  as  well  as  around  the  ootype,  altho 
they  are  not  so  numerous  in  the  former  as  in  the  latter  location.  The 
vaginae  open  to  the  surface  on  either  side  at  the  ventro-lateral  margins 
of  the  body,  at  the  level  of  the  posterior  margin  of  the  ovary  (Fig.  16). 
On  either  side  the  inner  ends  of  the  vaginae  unite  just  below  the  ceea 
with  the  common  ducts  from  the  vitellaria  to  form  the  vitello-vaginal 
canals.  These  open  separately  and  directly  into  the  ootype.  The  %'itel- 
laria  consist  of  large  compact  follicles,  underlying  the  entire  dorsal 
surface  of  the  body  from  the  pharynx  to  the  caudal  disc,  except  the 
region  over  the  ovary.  The  vitellaria  are  reduced  and  only  a  few  folli- 
cles are  present  in  the  region  over  the  testis  and  they  are  entirely  absent 
in  a  circular  area  over  the  ovary.  Ventrally  the  vitellaria  do  not  extend 
mediad  of  the  ceca.  The  vitellaria  are  so  extensively  developed  that  they 
obscure  the  internal  structures  and  render  the  body  opaque,  and  this 
character  suggested  the  name  of  the  species.  Common  collecting  duets 
run  longitudinally  along  the  body  lateral  to  the  intestinal  diverticula 
and  these  discharge  into  the  vitello-vaginal  canals  as  previously  de- 
scribed. In  each  of  the  specimens  there  is  a  single  large  egg  in  the 
uterus,  and  in  the  one  sectioned  the  uterus  extends  cephalad  of  the 
genital  pore  and  to  a  point  0.03  mm.  from  the  bifurcation  of  the  intes- 
tine. The  eggs  are  broadly  oval,  0.25  mm.  long  by  0.2  mm.  wide.  The 
shell  is  yellow,  refractive  to  light,  and  apparently  composed  of  the  same 
substance  that  occurs  in  small  droplets  in  the  vitellaria. 

The  uterus  and  cirrus  sac  open  into  the  genital  sinus;  the  opening 
of  the  cirrus  is  anterior  and  dorsal  to  that  of  the  uterus.  The  common 
genital  pore  is  situated  in  the  median  line,  about  0.12  mm.  caudad  of 
the  bifurcation  of  the  intestine.  Embedded  in  the  wall  of  the  cirrus  sac 
and  with  their  points  forming  the  so-called  coronet,  the  genital  hooks 
in  appearance  suggest  the  corolla  of  a  flower.  There  are  thirtj'-three 
of  these  hooks  in  one  mounted  specimen  and  thirty-two  in  the  other.  In 
entire  length  they  measure  0.05  mm.,  the  shank  or  projecting  part  com- 
prising about  half  the  total  length. 

P.  opacum  agrees  with  P.  alluaudi  and  P.  orhiculare  in  shape  of 
caudal  disc,  but  P.  alluaudi  has  but  three  spines  in  the  genital  coronet, 
and  a  long  post-ovarian  uterus  which  contains  many  eggs.  P.  orhiculare 
has  a  larger  anterior  sucker,  smaller  caudal  suckers,  a  smaller  pharj-nx, 
fewer  vitelline  follicles,  and  only  half  as  many  hooks  in  the  genital 
coronet.  P.  opacum  differs  from  P.  coronatum  and  P.  microcotijle  in 
the  shape  of  the  caudal  disc  and  in  the  reduced  condition  of  the  great 
hooks  of  the  disc. 


317]  NORTH  AMERICAN  POLYSTOMIDAE—STUNKARD  37 

POLYSTOMA   MEGACOTYLE  Stunkard  1916 
[Figures  22  to  26] 

The  material  of  this  species  consists  of  three  specimens  from  the 
mouth  of  Chrysemys  marginata  from  Creston,  Iowa.  One  worm  was 
cut  into  cross  sections  and  the  other  two  mounted  as  stained  toto 
preparations. 

These  worms  (Fig.  22)  have  an  elongate  ovoid  shape.  Widest  in 
the  region  just  anterior  to  the  caudal  disc,  they  gradually  become  nar- 
rower anteriorly,  and  posteriorly  they  taper  rapidly  to  a  caudal  tip 
which  is  set  in  thfe  antero-central  part  of  the  caudal  disc.  The  worms 
are  2.5  to  2.7  mm.  long  and  0.71  to  0.78  mm.  in  width.  The  caudal  disc 
is  cordiform  and  the  suckers  are  so  large  that  they  slightly  overlap  each 
other.  The  suckers  are  arranged  in  about  four-fifths  of  a  circle  around 
the  lateral  and  caudal  margins  of  the  disc.  Measurements  thru  the  disc 
from  side  to  side  at  the  level  of  the  cephalic  suckers  are  from  1  to  1.4 
mm.,  thru  the  middle  pair  1.2  to  1.8  mm.,  and  thru  the  caudal  suckers 
0.68  to  0.7  mm.  The  disc  bears  the  characteristic  armature  of  hooks. 
Across  the  anterior  margin  there  are  three  larval  booklets  in  one  speci- 
men and  four  in  the  other,  but  their  arrangement  is  not  regular  or 
definite  and  their  position  would  indicate  that  they  do  not  function  in 
attachment.  In  the  specimen  reproduced  in  Figure  22  the  two  hooks 
of  the  right  side  have  their  points  almost  together  and  their  bases  apart. 
In  the  bases  of  the  suckers  there  are  small  larval  booklets,  and  one  pair 
similar  in  size  and  shape  between  the  two  caudal  suckers.  Also  between 
the  posterior  suckers  (Fig.  41)  there  is  the  pair  of  great  hooks  and  a 
pair  of  hooks  the  same  shape  as  the  great  hooks  and  intermediate  in  size 
between  the  great  and  larval  hooks.  The  hooks  measure  in  length :  lar- 
val 0.017  mm.,  great  hooks  0.116  mm.,  and  the  pair  intermediate  in  size 
0.058  mm. 

The  cuticular  covering  of  the  body  is  approximately  5/a  in  thick- 
ness on  the  dorsal  and  3  to  4/a  in  thickness  on  the  ventral  surface.  It 
is  turned  in  at  the  external  openings  and  lines  the  digestive  tract  to  the 
bifurcation. 

The  anterior  sucker  is  set  off  from  the  remainder  of  the  body  by 
a  slight  constriction.  It  is  oval,  its  longest  axis  crosswise  of  the  body, 
somewhat  flattened  posteriorly,  and  measures  0.28  mm.  in  length  by 
0.35  to  0.42  mm.  in  width.  It  is  followed  by  the  pharynx  (Fig.  25) 
which  is  0.35  to  0.38  mm.  long,  0.38  to  0.44  mm.  broad,  and  in  the  sec- 
tioned worm  0.34  thick.  No  esophagus  was  observed;  the  ceca  meet 
anteriorly  in  a  wide  curve  and  extend  almost  to  the  posterior  end  of  the 
body.    They  are  0.06  to  0.11  mm.  in  diameter,  and  have  an  epithelial 


38  ILLINOIS  BIOLOGICAL  MOXOGRAPHS  [318 

lining  0.017  to  0.035  mm.  in  thickness  set  upon  a  fibro-membranous  base. 
The  vitellaria  are  so  thick  that  the  diverticula  can  not  be  traced  in  toto 
preparations. 

The  testis  is  situated  near  the  center  of  the  body;  it  is  spherical 
or  oval,  0.28  to  0.33  mm.  long,  0.33  to  0.38  ram.  wide,  and  in  the  sec- 
tioned worm  0.28  mm.  thick.  The  course  of  the  vas  deferens  and  the 
character  of  the  male  organs  are  similar  to  those  in  the  previously 
described  species.  The  genital  coronet  contains  thirty-six  hooks  in  one 
and  forty-two  in  the  other  toto  preparation.  They  are  similar  in  size 
and  shape,  have  a  straight  basal  portion  with  bifid  end  which  is  embedded 
in  the  wall  of  the  cirrus  sac,  and  a  sickle  shaped  shank  which  projects 
into  the  genital  atrium.  The  basal  portion  is  the  same  length  as  the 
shank  and  each  part  measures  0.03  mm. 

The  ovary  (Fig.  23)  is  a  broad  comma-shaped  organ,  situated  about 
midway  between  the  pharynx  and  testis,  on  either  side  of  the  body. 
The  larger  part  is  anterior  and  ventral  and  contains  many  nuclei  of 
forming  ova,  and  there  are  zones  of  developing  ova,  each  with  larger 
and  fewer  cells  until  dorsally  and  posteriorly  the  oviduct  is  given  oflP. 
The  oviduct  passes  mediad,  expanding  slightly,  and  then  posteriad  and 
ventrad  to  open  into  the  ootype.  This  structure  is  in  the  ventral  part 
of  the  body,  just  anterior  to  the  testis  (Fig.  24)  ;  from  the  sides  it  re- 
ceives the  vitello-vaginal  canals  and  gives  off  the  genito-intestinal  canal. 
This  canal  after  winding  in  a  double  loop  opens  into  the  intestine  on  the 
same  side  as  the  ovary.  It  was  empty  in  the  sectioned  worm.  The 
external  openings  of  the  vaginae  are  situated  on  small  prominences 
ventro-lateral  in  position,  altho  there  is  a  single  large  opening  to  the 
exterior.  The  vitellaria  consist  of  masses  of  follicles  occupying  the  dor- 
sal and  lateral  areas  of  the  body.  They  form  a  sheet  of  gland  cells  on 
the  dorsal  side  of  the  body  posterior  to  the  testis.  They  are  somewhat 
reduced  along  the  median  dorsal  area  in  the  anterior  half  of  the  worm 
and  entirely  absent  only  in  small  fields  over  the  testis  and  uterus.  They 
extend  along  the  sides  of  the  body  and  ventrally  are  limited  by  the  ceca. 
On  either  side,  at  the  level  of  the  ootype,  a  common  duct  from  the  longi- 
tudinal collecting  ducts  passes  ventrad  and  just  below  the  cecum  unites 
with  the  vagina  of  that  side  to  form  the  vitello-vaginal  canal  which 
discharges  into  the  ootype.  The  uterine  duct  leads  to  the  uterus,  which 
in  each  of  the  specimens  contained  a  large  egg.  A  section  of  the  egg  is 
shown  in  Figure  23.  The  eggs  are  oval,  0.15  by  0.18  mm.,  and  in  the 
sectioned  worm  the  egg  is  0.24  mm.  in  thickness.  From  the  uterus  a 
small  duct  passes  anteriad  and  ventrad,  opening  into  the  genital  atrium, 
posterior  and  ventral  to  the  cirrus  sac. 

The  excretory  system  agrees  with  the  general  description  given. 


319]  NORTH  AMERICAN  POLYSTOMIDAE-STUNKARD  39 

The  descending  and  ascending  ducts  are  6  to  11/t  in  diameter ;  when 
empty  their  walls  collapse. 

P.  megacotyle  differs  from  all  known  American  forms  in  the  large 
number  of  hooks  present  in  the  genital  coronet,  and  in  this  character 
agrees  only  with  P.  ocellatum.  The  species  differs  from  P.  ocellatum, 
however,  in  the  difference  in  size  of  the  anterior  sucker  and  pharynx 
as  well  as  in  the  size  of  the  caudal  suckers.  P.  megacotyle  differs  from 
P.  microcotyle  in  the  number  of  genital  hooks  and  in  the  size  of  the 
posterior  suckers.  P.  megacotyle  has  a  larger  pharynx,  larger  caudal 
suckers,  and  a  larger  number  of  gental  hooks  than  P.  coronatum. 

I 
POLYSTOMA   MICROCOTYLE    Stunkard  1916 

[Figures  28  and  29] 

This  species  is  described  from  a  single  specimen  from  the  mouth 
of  Chrysemys  marginata  from  Creston,  Iowa.  The  worm  was  stained 
and  mounted  in  toto  (Fig.  28). 

It  is  3  mm.  long,  and  0.78  mm.  in  width.  The  caudal  disc  is  cordi- 
form,  1  mm.  in  width  at  the  level  of  the  anterior  suckers,  1.07  mm. 
thru  the  middle  pair,  and  0.74  mm.  thru  the  caudal  pair  of  suckers. 
Each  sucker  is  0.28  mm.  in  diameter  and  with  the  exception  of  the 
longer  distance  between  the  anterior  suckers,  they  are  separated  by 
almost  regular  equal  distances.  The  distance  between  the  anterior 
suckers  is  about  four  times  as  great  as  that  between  the  posterior  pair. 
Four  larval  booklets  are  present  between  the  two  anterior  suckers,  three 
in  a  row  but  with  their  hooks  pointing  in  different  directions,  and  the 
fourth  some  distance  posterior  to  the  others  (Fig.  29).  Between  the 
posterior  suckers  there  are  three  pairs  of  hooks :  the  pair  of  great  hooks, 
one  pair  of  larval  hooks,  and  a  third  pair  intermediate  in  size  between 
the  great  and  larval  hooks.  The  hooks  of  this  third  pair  are  the  same 
shape  as  the  great  hooks.  The  larval  hooks  are  0.017  mm.  long,  the 
great  hooks  are  0.116  mm.  long,  and  the  pair  intermediate  in  size  are 
0.061  mm.  long. 

In  this  specimen  as  the  suckers  are  small  the  musculature  of  the 
caudal  disc  shows  very  plainly  (Fig.  29).  Muscle  strands  from  the 
ventral  side  of  the  body  and  others  from  the  body  wall  pass  to  the  bases 
of  each  of  the  suckers.  Others  pass  to  the  outside  of  the  different  suck- 
ers and  are  inserted  on  the  distal  and  intermediate  zones  of  the  suckers, 
serving  as  retractors  in  the  operation  of  the  organs.  Many  break  up 
into  smaller  fibers  and  can  not  be  traced.  From  the  base  of  each  sucker 
the  muscles  spread  out  in  a  fan  shaped  manner  and  fibers  can  be  traced 
not  only  to  the  large  strands  from  the  body  wall  but  also  small  fibers 


40  ILLIXOIS  BIOLOGICAL  MOXOGRAPHS  [320 

pass  from  the  base  of  each  sucker  to  each  of  the  other  suckers,  ilany 
of  the  muscles  branch  and  ramify  thru  the  tissue  of  the  disc. 

The  anterior  sucker  is  0.2  mm.  long  and  0.42  mm.  wide ;  the  pharj'nx 
is  0.37  mm.  long  and  0.4  mm.  in  width.  No  esophagus  is  visible  in  the 
single  toto  preparation  and  only  the  anterior  part  of  the  intestine  can 
be  seen. 

The  testis  is  slightly  anterior  to  the  middle  of  the  body;  it  is  oval, 
0.36  mm.  in  length  and  0.42  nun.  in  width.  The  sperm  duct  can  be 
traced  dorsally  and  anteriorly;  eephalad  of  the  ovary  it  expands  into 
a  seminal  vesicle  which  stains  deeply  due  to  the  presence  of  spermatozoa. 
The  genital  coronet  contains  thirty-two  hooks,  equal  in  size  and  similar 
in  shape. 

The  ovarj'  is  on  the  left  side  of  the  body,  about  midway  between 
the  testis  and  the  genital  pore.  The  oviduct  arises  at  the  median  pos- 
terior margin  and  passes  mediad,  but  the  structure  of  the  ootype  could 
not  be  made  out.  The  uterus  can  be  distinguished  at  the  level  of  the 
ovary  on  the  opposite  side  of  the  body  and  is  empty.  Laterally  the 
vaginae  are  visible  and  the  vitello-vaginal  canals  can  be  traced  mediad 
a  short  distance  from  the  ceca.  The  viteUaria  are  strongly  developed, 
anteriorly  they  extend  to  the  middle  of  the  pharynx,  and  posteriorly 
to  the  caudal  disc.  There  is  a  strand  of  foUicles  across  the  body  from 
side  to  side  between  the  pharynx  and  the  level  of  the  genital  pore.  The 
foUicles  occupy  the  dorsal  and  lateral  regions  of  the  body  but  anteriorly 
are  reduced  in  the  median  area  and  are  absent  in  the  fields  over  the 
testis  and  ovary.  They  obscure  the  ceca  caudal  to  the  testis.  No  vitel- 
line ducts  were  seen. 

The  excretory  vesicles  appear  one  on  either  side  of  the  bodj*  dor- 
sally,  at  the  level  of  the  bifurcation  of  the  intestine. 

In  number  of  genital  hooks  this  specimen  agrees  only  with  P.  coro- 
notum  Leidy.  A  comparison  with  a  type  specimen  of  P.  coronatum 
shows  that  in  the  latter  form  the  pharynx  and  testis  are  much  smaller 
and  the  suckers  of  the  caudal  disc  are  much  larger. 

POLYSTOilA   CORONATUM   Leidy  1888 
[Figure  27] 

This  description  was  made  from  a  single  type  specimen  from  the 
United  States  National  Museum.  The  worm  was  stained  and  mounted 
in  toto. 

Leidy  (1888)  says  the  host  is  the  common  food  terrapin,  and  the 
previous  j'ear,  speaking  of  eating  terrapin,  he  mentions  Emys  pahistris 
and  Emys  rugosa.     Braun  (1879-1893)  lists  the  species  from  Cistudo 


321]  NORTH  AMERICAS  POLYSTOMIDAE—STUNKARD  41 

Carolina.  Goto  (1899)  in  discussing  the  specimen  described  by  Leidy 
as  P.  ohloiigum,  refers  to  the  food  terrapin  as  E.  rugosa. 

Leidy  gives  no  figure  and  his  description  states :    " Polystomum  coro- 

natum Body  when  elongate  lanceolate.    Caudal  disc  wider 

than  the  body,  cordiform,  with  three  pairs  of  bothria  and  with  the  body 
attached  between  the  anterior  two  pairs;  changeable  in  form  to  oblong, 
circular  or  quadrate;  with  three  pairs  of  minute  hooks  between  the 
anterior  part  of  bothria  and  with  a  larger  pair  and  two  smaller  pairs 
between  the  last  pair  of  bothria.  Genital  aperture  with  a  circular  or 
transverse  oval  coronet  of  thirty-two  hooks  of  equal  length.  No  eyes 
visible.  Length,  elongated  from  4  to  6  mm;  contracting  to  about  half 
the  length  and  widening  proportionately." 

The  specimen  from  which  the  present  description  was  made  (Fig. 
27)  is  3.15  mm.  long  and  0.83  mm.  in  width.  The  greatest  width  is  at 
the  level  of  the  vaginae;  the  body  tapers  rapidly  anteriorly,  widening 
again  slightly  at  the  anterior  sucker.  From  the  level  of  the  vaginae 
the  body  gradually  grows  narrower  posteriorly  to  its  insertion  into  the 
caudal  disc.  The  disc  is  1.24  mm.  wide  at  the  level  of  the  anterior 
suckers,  1.2  mm.  thru  the  middle  pair  and  0.78  mm.  thru  the  caudal  pair 
of  suckers.  Each  sucker  is  approximately  0.37  mm.  in  diameter,  and 
constructed  as  previously  described.  There  are  thirty- two  small  di- 
visions in  the  peripheral  cuticular  band  of  the  only  sucker  in  which  they 
could  be  counted.  The  disc  bears  the  usual  eighteen  hooks;  the  six 
larval  booklets  at  the  anterior  margin  of  the  disc  are  situated  in  a  row 
equidistant  from  the  anterior  edge  of  the  disc,  the  two  lateral  hooks 
on  either  side  are  nearer  each  other  than  the  more  centrally  located  one 
is  to  the  median  one  of  that  side.  Larval  booklets  are  present  in  the 
bases  of  the  suckers  and  one  pair  is  present  between  the  caudal  suckers. 
Between  the  caudal  suckers  there  are  present  also  both  a  pair  of  great 
hooks  and  a  third  pair  intermediate  in  size  between  the  two.  The  larval 
booklets  are  0.02  mm.  in  length,  the  hooks  of  intermediate  size  are  0.051 
mm.,  and  the  great  hooks  are  0.132  mm. 

The  anterior  sucker  is  oval,  0.16  mm.  long  and  0.4  mm.  wide;  the 
pharynx  is  circular  in  outline,  0.3  mm.  in  diameter.  No  esophagus  can 
be  seen  in  the  toto  preparation  and  behind  the  posterior  margin  of  the 
testis  the  ceca  are  obscured  by  the  viteUaria. 

The  testis  is  slightly  anterior  to  the  center  of  the  body,  circular  in 
outline,  and  0.3  mm.  in  diameter.  The  vas  deferens  could  not  be  distin- 
guished; the  cirrus  sac  in  ventral  aspect  is  0.19  mm.  in  diameter;  the 
genital  coronet  contains  thirty-two  hooks,  similar  in  size  and  shape,  the 
shanks  being  sickle-shaped. 

The  ovary  is  situated  on  the  right  side  of  the  body,  about  its  own 


«  ILLINOIS  BIOLOGICAL  MONOGRAPHS  [322 

diameter  anterior  to  the  testis;  in  ventral  view  it  is  circular,  0.094  mm. 
in  diameter.  The  oviduct  passes  posteriad  and  mediad,  and  the  ootype 
appears  as  a  darkly  stained  area.  The  vaginae  can  be  distinctly  seen 
and  laterad  of  the  ceca  on  either  side  there  is  a  large  cavity  communi- 
cating with  the  exterior.  The  uterus  is  empty;  the  folded  walls  of  the 
cavity  are  visible  on  the  left  side  of  the  body.  The  vitellaria  are  strongly 
developed.  Masses  of  follicles  occupy  the  dorsal  and  lateral  regions  of 
the  body  but  ventrally  do  not  extend  mediad  of  the  ceca.  Anteriorly 
they  extend  to  the  region  of  the  pharynx;  there  is  a  strand  across  the 
body  just  behind  the  pharynx  and  in  the  intereecal  area  anterior  to  the 
testis  they  are  largely  interrupted,  permitting  the  structures  in  this 
region  to  be  made  out.    None  of  the  vitelline  ducts  are  ^'isible. 

The  excretory  vesicles  are  anterior  to  and  slightly  laterad  of  the 
ceca  at  the  level  of  the  caudal  margin  of  the  pharynx,  but  no  ducts 
could  be  seen. 

POLYSTOilA   HASSALLI   Goto  1899 

[Figures  30  to  33] 

This  species  was  described  by  Goto  (1899)  from  the  urinary  blad- 
der of  Cinosternum  pennsylvaniciim  from  Maryland.  The  writer  has 
since  collected  the  species  from  other  hosts  and  localities.  A  single 
specimen  was  found  in  the  urinary  bladder  of  Aromochelys  carinatus 
from  Newton,  Texas;  five  were  collected  from  the  urinary  bladder  of 
Aromochelys  odoratus  from  Raleigh,  North  Carolina;  two  from  the 
urinary  bladder  of  Cinosternum  pennsylvaiiicum,  from  Ealeigh,  N.  C. ; 
and  three  from  the  urinary  bladder  of  Chelydra  serpentina  from  Walker, 
Iowa. 

The  worms  (Figs.  30,  31)  vary  from  1.3  to  2  mm.  in  length  and 
from  0.4  to  0.65  mm.  in  width.  The  caudal  disc  varies  in  shape  from 
hexagonal  to  cordiform  and  is  of  approximately  the  same  width  as  the 
body.  The  suckers  are  0.12  to  0.16  mm.  in  diameter.  The  eighteen 
hooks  of  the  caudal  disc  have  the  usual  arrangement  and  are  described 
by  Goto.  However,  he  reports  the  larval  hooks  as  being  0.33  mm.  in 
length  and  the  great  hooks  between  the  caudal  suckers  as  0.125  mm.  in 
length.  This  is  evidently  a  typographical  error,  since  he  figured  the 
great  hooks  as  about  four  times  the  size  of  the  small  ones.  In  the  pres- 
ent material  the  great  hooks  are  the  same  length  as  stated  by  Goto  and 
the  smaller  ones  are  0.033  mm.  in  length,  which  agrees  with  the  figures 
of  Goto  by  a  change  of  one  place  in  the  decimal  point. 

The  anterior  sucker  is  ovoid,  more  pointed  anteriorly.  It  may  be 
longer  in  either  the  anterior-posterior  or  lateral  axis  and  varies  in  diame- 
ter from  0.22  to  0.33  mm.    The  pharynx  is  spherical  or  oval  and  varies 


323]  NORTH  AMERICAN  POLYSTOMIDAE—STUNKARD  43 

in  width  from  0.1  to  0.14  mm. ;  it  may  be  longer  in  either  axis.  There 
is  no  esophagus,  but  in  some  specimens  a  median  pocket  of  the  intestine 
extends  anteriad  from  the  bifurcation  to  the  pharynx.  In  others,  and 
this  is  a  more  usual  condition,  lateral  pockets  of  the  intestine  extend 
anteriad,  one  on  either  side  of  the  pharynx  (Fig.  33).  The  anterior 
sucker  and  pharynx  are  lined  with  cuticula;  the  intestine  with  the 
usual  digestive  epithelium.  In  those  specimens  in  which  the  uterus 
contains  an  egg,  the  large  size  of  the  egg  causes  the  ceca  to  be  widely 
separated  at  the  uterine  level  and  they  approach  each  other  behind  the 
uterus.  In  one  specimen,  median  branches  from  the  two  ceca  fuse  and 
form  a  posterior  connection  of  the  diverticula  (Fig.  30),  and  in  another 
the  two  ceca  are  united  at  their  ends. 

The  testis  is  situated  ventrally,  just  behind  the  middle  of  the  body. 
It  is  a  somewhat  shapeless  mass,  roughly  oval  in  outline,  crosswise  of 
the  body,  extending  between  the  ceca  just  posterior  to  the  uterus.  The 
vas  deferens  passes  anteriad,  dorsal  to  the  ovary  and  between  it 
and  the  uterus;  anterior  to  the  uterus  the  sperm  duct  turns  ventrad, 
enlarges  to  form  a  seminal  receptacle,  and  then  passes  thru  the  cirrus 
sac,  opening  into  the  genital  atrium  (Fig.  32).  The  cirrus  hooks  are 
sixteen  in  number,  0.028  mm.  in  length,  straight,  and  with  a  wing  like 
process  at  the  middle  as  described  by  Goto. 

The  ovary  is  comma  shaped  or  ovoid  in  outline,  situated  obliquely 
in  the  body,  on  either  the  right  or  left  side.  Typically  the  ovary  is  on 
one  side  of  the  body  and  the  uterus  on  the  other,  but  the  enormous  size 
of  the  egg  causes  the  uterus  to  occupy  a  more  or  less  central  position, 
crowding  the  ovary  far  to  one  side.  The  ovary  is  0.058  by  0.065  mm. 
in  the  smallest  and  0.085  by  0.12  mm.  in  the  largest  worms,  altho  the 
size  of  the  ovary  does  not  correspond  precisely  with  the  size  of  the 
worm.  The  oviduct  arises  at  the  dorsal  median  and  posterior  part  of 
the  ovary  and  after  a  dorsal  loop  it  turns  posteriad  and  ventrad  to  open 
into  the  ootype.  Mehlis'  gland  is  present.  The  genito-intestinal  canal 
branches  from  the  ootype  and  after  a  short  winding  course  opens  into 
the  intestine  near  the  ovary.  From  the  ootype,  the  uterine  duct  passes 
laterally  to  the  opposite  side  of  the  median  line  and  then  anteriorly 
and  dorsally  to  open  into  the  dorsal  posterior  part  of  the  uterus.  The 
vitellaria  extend  from  the  pharyngeal  region  to  the  anterior  margin 
of  the  caudal  disc;  there  is  a  row  of  follicles  across  the  dorsal  surface 
behind  the  pharynx  but  they  are  absent  between  the  ceca  anterior  to 
the  testis.  According  to  Goto,  "lobes  not  very  numerous,  separated 
from  one  another,  mostly  confined  to  the  lateral  portion  of  the  body, 
but  also  present  in  the  median  portion  behind  the  testis."  The  vaginae 
are  ventro-lateral,  midway  between  the  anterior  and  posterior  ends  of 
the  body.    There  are  no  vaginal  prominences,  the  vaginal  openings  are 


44  ILLINOIS  BIOLOGICAL  MONOGRAPHS  [324 

single,  and  internally  they  unite  with  ducts  from  the  longitudinal  vitel- 
line ducts  to  form  the  vitello-vaginal  canals,  as  described  for  the 
other  species.  They  do  not  open  separately  into  the  ootype,  but  the 
two  vitello-vaginal  canals  open  into  a  common  reservoir  from  which  a 
duct  passes  dorsad  and  discharges  into  the  ootype  (Fig.  32).  In  a  few 
of  the  specimens  the  uterus  is  empty  and  in  others  it  contains  a  single 
large  egg,  the  size  of  which  varies  within  wide  limits.  The  smallest 
eggs  are  0.11  by  0.25  mm.  and  the  largest  0.18  by  0.34  mm.  The  pos- 
terior edge  of  the  uterus  is  at  the  level  of  the  vaginae,  and  anteriorly 
there  is  a  small  duct  from  the  uterus  to  the  ventral  posterior  part  of 
the  genital  atrium.  The  genital  pore  is  in  the  median  line,  a  short 
distance  posterior  to  the  bifurcation  of  the  alimentary  tract. 

The  excretory  pores  are  slightly  more  posteriorly  situated  than  in 
the  previous  described  species.  Descending  and  ascending  ducts  occupy 
the  characteristic  positions. 

POLYSTOMA  OBLONGmi  Wright  1879 

This  species  was  described  by  "Wright  (1879)  from  the  urinary 
bladder  of  Aromochelys  odoratus.  I  have  had  no  opportunity  to  work 
on  material  of  the  species  and  the  following  discussion  is  based  on  the 
description  of  Wright.  According  to  that  author  P.  oblongum  measures 
up  to  2.5  mm.  in  length  and  1.5  mm.  in  width.  The  body  is  oblong  in 
shape,  tho  capable  of  considerable  variation.  The  caudal  lamina  is  some- 
what narrower  than  the  greatest  width  of  the  body  and  is  shorter  than 
broad.  The  arrangement  of  the  suckers  and  hooks  is  similar  to  that  in 
P.  integerrimum;  the  suckers  are  0.2  mm.  in  diameter;  the  large  hooks 
are  0.15  mm.  and  the  small  hooks  are  0.015  mm.  in  length. 

The  mouth  is  on  the  ventral  surface  of  the  rounded  anterior  end. 
The  pharynx  is  bowl-shaped  and  the  intestinal  ceca  are  without  anasto- 
moses or  branches.  The  description  of  the  excretory  system  is  very 
meager;  concerning  it  he  says  that  only  the  convoluted  lateral  stems 
were  observed  near  the  anterior  end. 

The  testis  is  situated  in  the  posterior  third  of  the  body,  the  vas 
deferens  passing  dorsad  and  anteriad  to  the  genital  pore,  which  lies  im- 
mediately behind  the  bifurcation  of  the  intestine.  The  cirrus  coronet  is 
described  as  consisting  of  sixteen  alternately  large  and  small  hooks.  The 
free  end  of  each  is  sharply  curved,  while  the  attached  end  is  shaped  like 
a  cross  the  transverse  piece  of  which  is  longer  on  one  side  than  the  other. 
The  longer  pieces  measure  20;ti  and  the  shorter  ones  15/x. 

Doubt  is  expressed  concerning  the  disposition  and  relations  of  the 
female  organs.  The  ovary  is  described  as  situated  in  front  of  the  testis 
on  the  right  side  of  the  body,  but  it  seems  probable  that  the  organ  figured 


325]  NORTH  AMERICAN  POLYSTOMIDAE—STUNKARD  45 

as  the  "  (shell  gland?) "  is  really  the  ovary.  The  lobes  of  the  vitellaria 
are  scattered  and  extend  from  the  pharynx  to  the  caudal  lamina  or  disc. 
It  is  doubtful  whether  Wright  was  correct  in  his  statement  that  "The 
transverse  duct  seemed  to  pass  inward  dorsally  from  the  intestinal  ceca," 
since  in  all  other  known  species  the  vitelline  ducts  are  ventral  in  position. 

The  uterus  is  described  as  containing  a  single  large  egg  or  embryo. 
The  egg  shell  is  thin  and  is  destitute  of  the  short  stump  present  in  that 
of  P.  integerrimum,  but  has  a  rather  large  operculum.  In  two  cases  the 
embryo  had  already  escaped  from  the  shell  and  moved  actively  within 
the  uterine  chamber.  It  is  a  Gyrodactylus-like  larva,  similar  to  that  of 
P.  integerrimum,  with  eye  spots  disposed  in  the  same  fashion.  It  is 
devoid  of  cilia,  and  movement  seemed  to  depend  entirely  on  the  muscles 
and  hooks  of  the  caudal  disc.  The  latter  had  a  rounded  outline  except 
posteriorly  where  there  was  a  square  projection  bearing  the  four  small 
posterior  hooks.  The  disc  measured  0.114  mm.  across  and  the  twelve 
small  anterior  hooks  were  disposed  at  regular  intervals  on  the  margin  of 
the  rounded  part.  There  was  no  trace  of  suckers.  The  small  hooks  had 
already  attained  their  definitive  size  and  form.  The  two  large  hooks 
were  situated  considerably  further  in  from  the  margin  than  in  the  adult, 
and  measured  only  0.024  mm.  instead  of  0.15  mm.  in  length,  which  dif- 
ference it  is  stated  was  due  to  the  shortness  of  the  immersed  portion,  in 
which,  however,  the  notch  was  already  formed. 

In  shape,  as  well  as  relative  position  and  size  of  organs,  P.  ohlongum 
strongly  resembles  P.  hassalli.  It  is  significant  also  that  both  are  from 
the  urinary  bladder  of  Aromochelys  odoratus.  P.  oblongum  is  slightly 
longer  and  broader  than  P.  hassalli,  the  posterior  suckers  are  larger  and 
the  small  hooks  of  the  disc  are  only  about  half  the  length  of  those  in 
those  in  P.  hassalli.  The  two  species  agree  in  number  of  genital  hooks, 
but  in  the  former  species  the  hooks  are  alternately  large  and  small  and 
with  the  free  end  sharply  curved,  while  in  P.  hassalli  they  are  straight 
and  uniform  in  size. 

The  species  in  the  genus  Polystoma  have  been  arranged  in  the  form 
of  an  analytical  key  utilizing  the  more  prominent  or  more  useful 
diagnostic  structures  in  separating  the  different  forms.  This  key  is 
found  on  the  following  page. 


46  ILf^INOIS  BIOLOGICAL  MONOGRAPHS  [326 

KEY  TO  THE  SPECIES  OP  THE  GENUS  POLYSTOMA 

Uterus  long,  contains  many  eggs 2 

Great  hooks  present  on  the  caudal  disc 3 

Ceca  branching P.  integerrimum 

Ceca  not  branching  P.  huUiense 

Great  hooks  not  present  on  caudal  disc P.  alluaudi 

Uterus  short,  contains  a  single  egg 7 

Great  hooks  present  on  caudal  disc 8 

Genital  hooks  of  equal  length 9 

Not  more  than  sixteen  genital  hooks 10 

Genital  hooks  eight  in  number; 

ectoparasitic  form P.  integerrimum 

Grenital  hooks  sixteen  in  number P.  hassalli 

Genital  hooks  more  than  sixteen  in  number 13 

Genital  hooks  thirty-two  in  number 14 

Caudal  suckers  large,  adjacent  but  not  contiguous, 

pharynx,  smaller  than  anterior  sucker P.  coranatum 

Caudal  suckers  small,  widely  separated,  pharynx  equal  in 

size  to  anterior  sucker P.  microcotyle 

Genital  hooks  more  than  thirty-two  in  number _.  17 

Testis  simple 18 

Caudal  suckers  large,  overlap P.  megacotyle 

Caudal  suckers  small,  separated P.  ocellatum 

Testis  branched P.  kachugae 

Genital  hooks  unequal  in  length P.  ohlongum 

Great  hooks  of  caudal  disc  reduced  or  absent . 23 

Genital  hooks  sixteen  in  number P.  oriiculare 

Genital  hooks  thirty-two  in  number P.  opacum 


1 

(  6) 

2 

(  5) 

3 

(  4) 

4 

(  3) 

5 

(  2) 

6 

(  1) 

7 

(22) 

8 

(21) 

9 

(12) 

10 

(11) 

11 

(10) 

12 

(  9) 

13 

(16) 

14 

(15) 

15 

(14) 

16 

(13) 

17 

(20) 

18 

(19) 

19 

(18) 

20 

(17) 

21 

(  8) 

22 

(  7) 

23 

(24) 

24 

(23) 

327]  NORTH  AMERICAN  ASPIDOGASTRIDAE—STUNKARD  47 


ASPIDOGASTRIDAE 

Because  of  its  peculiar  multiloculate  adhesive  apparatus,  Burmeister 
(1856)  called  attention  to  the  difference  between  the  genus  Aspidogaster 
and  the  remainder  of  the  trematodes,  and  suggested  a  division  of  the 
Trematoda  into  (1)  Malaeobothrii  for  the  distomes  and  holostomes, 
(2)  Pectobothrii  for  the  polystomes,  and  (3)  Aspidobothrii  for  Aspido- 
gaster. Subsequent  writers  however  continued  to  include  Aspidogaster 
with  the  polystomes  until  Monticelli  (1892)  revived  the  classification 
of  Burmeister,  but  named  the  three  suborders  into  which  he  divided  the 
trematodes,  Heterocotylea,  Aspidoeotylea,  and  Malacocotylea. 

In  the  classification  of  Monticelli,  the  Aspidoeotylea  contained  the 
single  family  Aspidobothridae.  Poche  (1907)  proposed  to  make  the 
name  of  the  family  agree  with  the  rules  of  zoological  nomenclature 
according  to  which  "The  name  of  the  family  is  formed  by  adding  the 
ending  -idae  to  the  stem  of  the  name  of  its  type  genus. ' '  Thus  the  name 
of  the  family  must  become  Aspidogastridae. 

The  family  is  of  special  interest  to  students  of  trematode  mor- 
phology. The  form  of  the  adhesive  apparatus,  with  its  retractile  mar- 
ginal organs,  the  separation  of  the  body  into  dorsal  and  ventral  portions 
by  a  muscular  partition,  the  sac-like  alimentary  tract,  and  the  details 
of  the  genital  organs  are  peculiar  to  the  group.  The  family  contains 
both  eetoparasitic  and  endoparasitic  species,  forms  with  direct  develop- 
ment and  at  least  one  species  which  has  an  intermediate  host,  while  the 
hosts  infested  by  the  adult  parasites  include  both  invertebrates  and 
vertebrates,  species  having  been  reported  from  molluscs,  fishes,  and 
turtles. 

Summaries  or  revisions  of  the  group  have  been  made  by  Diesing 
(1850,  1859),  Tasehenberg  (1879),  Hoyle  (1888),  MonticeUi  (1892), 
Braun  (1879-1893),  and  Nickerson  (1902). 

Only  three  species  representing  two  genera  of  the  family  are  known 
from  North  America,  Aspidogaster  conchicola  von  Baer  1827,  Cotylaspis 
insignis  Leidy  1856,  and  Cotylaspis  cokeri  Barker  and  Parsons  1914. 
Eepresentatives  of  each  of  these  species  were  available  for  the  present 
study.  The  first  two  species  are  well  known;  concerning  A.  conchicola 
no  further  data  were  obtained,  but  a  few  corrections  are  made  to  former 
descriptions  of  C.  insignis. 


48  ILLINOIS  BIOLOGICAL  MONOGRAPHS  [328 

Cotylaspis  cokeri  has  been  mentioned  but  once  in  print,  but  on  the 
basis  of  extended  studies  this  form  had  been  fully  described  and  its 
position  as  a  new  species  demonstrated  in  a  thesis  submitted  by  the 
writer  in  partial  fulfillment  for  the  degree  of  Master  of  Arts  in  the 
Graduate  school  of  the  University  of  Illinois  in  June  1914.  The  fol- 
lowing October  Barker  and  Parsons  (1914),  having  also  been  working 
on  this  form  independently,  published  a  brief  description  naming  it 
Cotylaspis  cokeri.  Since  I  had  completed  my  work  on  it  before  the 
appearance  of  their  note  and  the  publication  of  their  final  report  has 
been  delayed  it  seems  proper  to  give  here  a  detailed  description  of  the 
species. 

ASPIDOGASTER   CONCHIGOLA   von  Baer  1827 

About  fifty  specimens  from  the  pericardial  and  renal  cavities  of 
Andonta  corpulenta  from  Havana,  Illinois,  and  a  similar  number  of 
specimens  from  the  same  organs  of  Quadrula  undulata  from  North 
Judson,  Indiana,  constitute  the  material  of  this  species  available  for 
study. 

A  detailed  comparison  of  these  specimens  with  the  descriptions  of 
A.  conchicola  as  given  by  Voeltzkow  (1888),  Stafford  (1896),  and  other 
writers,  shows  that  they  belong  to  that  species  and  substantiates  the  obser- 
vations of  Leidy  (1851),  Kelly  (1899),  and  Kofoid  (1899),  that  A.  con- 
chicola occurs  in  this  country.  So  far  it  is  the  only  species  in  the  genus 
known  from  moUuscan  hosts. 

Kelly  (1899)  made  a  parasitological  examination  of  1537  individ- 
uals of  forty-four  species  of  unios  from  Mt.  Vernon,  Iowa,  Havana, 
Illinois,  and  Lewisburg  and  Phoenixville,  Pennsylvania,  and  included 
in  his  report  results  of  the  examination  of  seventy-seven  individuals 
belonging  to  eighteen  species,  made  by  Kofoid  in  1895  and  1896.  In 
four  hundred  thirty-five  cases  A.  conchicola  was  found  in  the  pericar- 
dium only,  in  seventy-five  in  the  kidneys  only,  and  in  one  hundred 
thirty-four  cases  both  cavities  contained  the  parasite.  The  presence  of 
the  mature  trematode  in  the  pericardium  and  of  eggs  within  the  nephri- 
dia  was  not  infrequent.  Of  the  1537  specimens  examined,  forty-one 
per  cent  were  parasitized  with  A.  conchicola  and  thirty-seven  of  the 
forty-four  species  were  infested  with  the  parasite. 

No  further  data  on  this  species  were  obtained  by  the  present  study. 


329]  XORTH  AMERICAN  ASPIDOGASTRIDAE—STUNKARD  49 

COTYLASPIS   INSIGNIS   Leidy  1856 
[Figure  56] 

The  material  of  this  species  consists  of  specimens  from  Anodonta 
inibecilis,  A.  corpulenta,  LampsUis  gracilis,  and  Unio  pustulosis  from 
Havana,  Illinois,  and  others  from  Anodonta  ferrus  and  A.  ovata  from 
Reed 's '  Lake  near  Grand  Rapids,  Michigan.  The  material  proved  to 
belong  to  the  same  species  and  was  identical  with  C.  insignis  Leidy. 

Leidy  first  discovered  the  parasite  in  the  Unionidae  of  the  Schuyl- 
kill River  and  founded  the  genus  to  receive  the  new  species.  His  generic 
and  specific  diagnosis  (1858)  follows:  "Body  curved  infundibuliform, 
anteriorly  eylindro-conical,  posteriorly  expanding  into  a  subcircular  or 
oval  ventral  disc  with  numerous  acetabula  arranged  in  a  triple  series. 
Mouth  infero-terminal,  with  prominent  upper  lip,  and  protractile  into 
a  cup  or  disc  like  acetabulum.  Intestinal  apparatus  as  in  Aspidogaster, 
eyes  two,  distinct,  black,  situated  on  either  side  of  the  head.  Generative 
apertures  inferior  between  the  head  and  ventral  disc." 

According  to  the  same  author,  C.  insignis,  the  type  species  is: 
' '  Translucent  white  or  pink  white,  upper  lip  snout  like,  conical,  ventral 
disc  crenate  at  the  margin :  acetabula  twenty-nine,  oblong  quadrate,  the 
outer  rows  continuous  in  front  and  behind  forming  a  circle.  Length 
from  one-half  to  one  line;  ventral  disc  from  one-fourth  to  one-half  line 
in  diameter.  Adheres  to  the  outer  surface  of  the  renal  organ  and 
upper  margin  of  the  foot,  within  the  cleft  of  the  upper  branchial  cavity 
of  Anodonta  fluviatUis  and  A.  lacustris." 

Forbes  (1896)  reported  this  parasite  in  the  river  clams  at  Havana, 
Illinois.  Osborn  (1898)  described  the  species  from  Lake  Chautauqua, 
New  York,  as  Platyaspis  anadantae.  Kofoid  (1899)  corrected  this 
error,  demonstrating  that  Leidy 's  genus  is  entitled  to  recognition,  and 
establishing  the  specific  identity  of  Platyaspis  anadantae  Osborn  with 
C.  insignis  Leidy.  Kelly  (1899)  reporting  on  the  examination  of  over 
sixteen  hundred  individuals  of  forty-four  species  of  Unionidae  found  the 
parasite  in  twenty-four  different  species  of  molluscs  and  in  eighteen  per 
cent  of  the  individuals  examined. 

Osborn  (1904)  gives  a  review  of  the  literature,  an  account  of  the 
distribution,  habits,  external  and  internal  anatomy  of  the  mature  worm, 
and  a  description  of  a  very  young  individual.  The  young  specimen 
described  has  a  simple  ventral  sucker,  no  eye  spots,  no  marginal  organs, 
two  entirely  distinct  excretory  systems,  and  wholly  separate  pores.  This 
condition  of  the  excretory  system  is  compared  with  the  condition  in 
redia  and  cercaria  and  according  to  Osborn  favors  the  idea  suggested 
by  Leuckart  that  the  Aspidogastridae  are  sexually  mature  redia. 


so  ILUNOIS  BIOLOGICAL  MONOGRAPHS  [330 

COTYLASPIS   COKERI   Barker  and  Parsons  1914 
[Figures  46  to  55,  57,  58] 

From  four  to  twenty-five  specimens  were  found  in  the  intestine 
of  each  of  seven  specimens  of  Malacoclemmys  lesueurii  from  Newton, 
Texas. 

The  worms  (Figs.  46,  47,  52)  average  1.5  mm.  in  length  by  0.7 
mm.  in  width,  altho  there  is  considerable  variation  in  relative  length 
and  width  due  to  the  movements  of  the  animal.  The  body  is  composed 
of  two  parts,  an  anterior  dorsal  forebody  and  a  posterior  ventral  adhe- 
sive disc.  "When  extended  (Fig.  46),  the  forebody  has  the  shape  of  a 
cornucopia,  the  larger  end  attached  obliquely  to  the  central  two-thirds 
of  the  dorsal  surface  of  the  adhesive  disc.  In  this  condition  the  worm 
has  an  elongate  form,  projecting  beyond  the  adhesive  disc  a  distance 
equal  to  the  length  of  that  structure:  in  a  retracted  condition  (Fig.  52) 
it  is  compact  and  may  not  project  beyond  the  disc.  The  total  length 
of  the  worm  varies  therefore  with  the  state  of  extension  of  the  forebody, 
from  the  length  of  the  adhesive  disc  to  twice  that  distance. 

The  adhesive  disc  (Figs.  47,  57)  is  a  muscular  organ,  a  multilocu- 
late  sucker,  used  for  attachment  and  locomotion.  It  has  a  crenate  oval 
outline,  the  dorsal  surface  is  arched,  and  the  ventral  surface  is  flattened. 
The  ventral  surface  is  divided  by  two  longitudinal  and  eleven  cross 
ridges  into  thirty-two  acetabula,  which  are  arranged  in  three  rows; 
there  are  twenty-two  •  peripheral  alveoli  enclosing  ten  median  alveoli. 
In  this  statement,  the  alveolus  at  either  end  is  counted  in  the  peripheral 
rather  than  the  median  row,  tho  in  location  included  in  both.  These 
compartments  change  in  shape  with  the  movements  of  the  animal,  be- 
coming oval  or  quadrangular.  The  shape  and  size  of  the  disc  are  rela- 
tively constant,  measurements  of  the  disc  in  twenty  mounted  toto  speci- 
mens vary  only  from  1.2  to  1.4  mm.  in  length  and  from  0.58  to  0.78 
mm.  in  width.  This  structure  recalls  the  moUuscan  foot,  and  it  has 
often  been  termed  the  foot  altho  the  morphological  comparison  is  not 
precise. 

Movement  consists  of  extension  of  the  forebody,  which  furthermore 
may  be  turned  in  any  direction,  and  in  the  less  striking  and  more  re- 
stricted movement  of  the  disc.  The  disc  has  a  tendency  to  turn  up  at 
the  edges,  especially  at  the  anterior  and  posterior  ends.  In  adhesion 
the  organ  may  act  as  a  unit,  or  the  separate  alveoli  may  function  inde- 
pendently. In  locomotion  there  is  a  regular  series  of  movements,  the 
forebody  is  extended  and  attached  by  the  sucking  action  of  the  mouth 
funnel,  then  the  disc  is  loosened  and  the  forebody  contracted,  bringing 
the  anterior  part  of  the  disc  near  the  mouth,  when  the  disc  is  attached 


331]  NORTH  AMERICAN  ASPIDOGASTRIDAE—STUNKARD  51 

and  the  series  of  movements  repeated.  The  worm  moved  rapidly  across 
the  field  of  the  microscope. 

Body  Covering. — Externally  the  worms  are  covered  by  a  non- 
cellular  cuticula,  which  is  thickest  on  the  dorsal  side  of  the  body  and 
thinnest  on  the  ventral  surface  of  the  adhesive  disc  (Figs.  49,  53).  It 
is  without  hooks  or  spines,  and  on  the  dorsal  surface  reaches  a  thickness 
of  5/1,  while  on  the  ventral  surface  of  the  disc  it  is  only  about  1/*  in 
thickness.  The  cuticula  is  turned  in  at  the  external  openings  and  lines 
the  external  portions  of  the  canals  of  the  alimentary,  excretory  and 
reproductive  systems. 

Musculature. — Immediately  inside  the  cuticula  is  the  three  layered 
dermo-muscular  wall,  circular  longitudinal  and  oblique  muscles  occur- 
ring in  the  order  mentioned,  the  circular  lying  next  to  the  cuticula 
and  in  all  parts  of  the  wall  being  better  developed  than  the  others.  The 
musculature  is  delicate  and  in  some  places  the  longitudinal  and  oblique 
muscles  are  very  scanty.  The  musculature  of  the  ventral  side  of  the 
forebody  is  continued  posteriorly  in  a  thin  sheet,  the  so-called  septum 
or  diaphragm  (Fig.  53),  which  lies  just  above  the  limiting  membrane 
of  the  musculature  of  the  disc  and  extends  posteriad  as  far  as  the  caudal 
end  of  the  cirrus  sac.  In  C.  insignis  Osborn  described  this  structure 
as  passing  posteriad  as  far  as  the  caudal  end  of  the  ovary  and  in  other 
genera  it  is  more  strongly  developed.  The  parenchymous  muscles  of 
the  body  are  long,  often  much  branched,  and  most  abundant  in  locations 
where  they  connect  different  parts  of  the  body  wall  with  each  other  or 
with  adjacent  internal  structures.  In  the  anterior  part  are  many  well 
developed  muscles  of  this  type  used  in  the  movement  of  that  region. 
Running  longitudinally  among  the  vitellaria,  as  well  as  dorso-ventrally 
among  the  viscera  there  are  many  muscle  fibers.  Sphincters  and  dilators 
occur  at  the  genital  pore,  excretory  pore,  at  the  base  of  the  mouth  funnel, 
and  at  the  opening  between  the  pharynx  and  the  intestine. 

The  disc  is  separated  from  the  forebody  by  a  limiting  membrane 
(Figs.  49,  53).  This  membrane  runs  parallel  to  the  general  course  of 
the  external  ventral  surface  of  the  disc,  projecting  ventrad  at  each 
ridge.  Extending  between  this  membrane  and  the  external  wall  there 
are  muscle  fibers,  often  much  branched  especially  at  the  ends.  The 
ventral  projections  of  the  limiting  membrane  into  the  ridges  of  the 
disc  form  two  sides  of  long  triangular  prisms,  which  extend  longitudi- 
nally and  transversely  above  the  musculature  of  the  disc.  One  face 
of  each  of  these  prisms  is  dorsal  and  the  opposite  angles  extend  ventrad 
forming  the  ridges  which  separate  the  disc  into  fossettes.  These  ridges 
are  composed  of  fibrous  connective  tissue  in  which  a  few  nuclei  are 
embedded. 


52  ILLINOIS  BIOLOGICAL  MONOGRAPHS  [332 

I 
Alimentary  Tract. — The  mouth  funnel  is  a  cup  shaped  muscular 
structure  (Fig.  51)  which  functions  as  an  organ  of  adhesion.  There 
is  no  oral  sucker.  The  mouth  funnel  is  0.08  to  0.1  mm.  in  diameter, 
sub-terminal  in  position.  There  is  no  prepharynx,  the  mouth  funnel 
opens  directly  into  the  pharynx.  The  latter  is  a  spherical  muscular 
organ  0.09  to  0.1  mm.  in  diameter.  As  described  by  Osboru  for  C. 
insignis,  it  is  followed  by  a  very  short  esophagus,  which  in  the  anterior 
part  has  a  cuticular  lining  and  in  the  posterior  part  where  the  esopha- 
gus passes  over  into  the  intestine,  a  lining  of  flattened  epithelial  cells. 
The  intestine  is  an  elongate  sac  or  tube  extending  on  the  dorsal  side 
of  the  body  0.1  to  0.2  mm.  posterior  to  the  caudal  edge  of  the  testis. 
It  varies  but  slightly  in  caliber,  averaging  about  0.075  mm.  in  diameter. 
The  wall  consists  of  a  fibro-membranous  sheet  upon  which  rests  a  layer 
of  columnar  epithelial  cells.  The  large  deeply  staining  nuclei  of  the 
epithelial  cells  lie  in  the  basal  part  while  many  delicate  elongate  proc- 
esses extend  out  into  the  lumen  of  the  canal. 

Male  Reproductive  Organs. — The  testis  is  large,  single,  median,  its 
anterior  margin  lying  at  the  center  of  the  adhesive  disc.  It  is  almost 
spherical  and  measures  0.25  to  0.35  mm.  in  diameter.  Cells  of  various 
sizes  and  with  the  chromatin  material  in  various  stages  of  division,  as 
well  as  mature  spermatozoa  are  to  be  seen  in  sections.  The  sperm  duet 
arises  at  the  anterior  part  of  the  testis  and  turns  to  the  left,  entering 
the  side  of  a  long,  much-coiled  seminal  vesicle  (Fig.  48).  This  vesicle 
is  a  large  tube,  0.1  to  0.175  mm.  in  diameter,  extending  from  the  region 
of  the  testis  to  the  cirrus  sac.  It  is  coiled  eight  to  sixteen  times  and  in 
aU  mature  specimens  is  filled  with  spermatozoa.  Terminally  it  is  con- 
stricted into  a  small  tube  which  enters  the  large  cirrus  sac.  This  latter 
structure  (Fig.  53)  is  0.145  to  0.2  mm.  wide  and  0.2  to  0.25  mm.  long, 
has  a  strong  muscular  wall,  and  is  pyriform  in  shape,  the  smaller  end 
opening  anteriorly  at  the  genital  pore.  Inside  the  cirrus  sac  there  is 
a  dilated,  curved  portion  of  the  duct  which  has  muscular  walls  and  is 
lined  with  epithelial  cells.  Surrounding  the  duct  and  filling  the  cirrus 
sac  are  the  large  cells  of  the  prostate  gland.  These  are  pyriform  and 
average  26/n  long  by  17/i  wide.  In  living  specimens  the  cirrus  was 
observed  in  the  extruded  condition. 

Female  Reproductive  Organs. — The  ovary  is  a  small  organ,  ovoid 
in  shape,  averaging  0.16  mm.  in  length,  0.1  mm.  in  width,  and  0.05  mm. 
in  thickness.  It  is  located  (Figs.  46,  52)  at  the  right  of  the  median 
line,  slightly  anterior  to  the  middle  of  the  body.  The  oviduct  arises 
(Fig.  48)  at  the  posterior  ventral  margin  of  the  ovary  and  passes 
posteriad;  receives  a  short  common  vitelline  duct,  and  then  expands 
into  two  or  three  irregular  enlargements.    Mehlis'  gland  is  present,  the 


333]  NORTH  AMERICAN  ASPIDOGASTRIDAE—STUNKARD  53 

nuclei  lying  in  the  parenchyma  around  the  ootype.  The  uterus  passes 
posteriad  on  the  lateral  side  of  the  collecting  duct  of  the  excretory 
system  as  far  as  the  caudal  end  of  the  testis  where  it  turns  to  the  median 
line.  It  passes  ventrad  and  anteriad  beneath  the  testis ;  in  front  of  the 
testis  it  turns  dorsad  and  toward  the  ovary,  but  just  before  reaching 
the  ovary  it  turns  and  crosses  to  the  opposite  side  of  the  body  and  then 
passes  with  little  deviation  to  the  genital  pore.  There  is  a  strong  sphinc- 
ter at  the  distal  end  of  the  uterus  (Fig.  54).  Eggs  were  present  at 
various  places  in  the  course  of  the  uterus  and  when  the  worms  were 
placed  in  tap  water,  the  eggs  near  the  pore  were  extruded.  The  eggs 
are  few  in  number,  not  more  than  six  being  present  in  any  specimen. 
They  vary  from  0.071  to  0.086  mm.  in  width  and  from  0.137  to  0.145 
mm.  in  length.    The  average  of  twenty-five  is  0.075  by  0.141  mm. 

The  vitellaria  (Figs.  46,  49)  are  arranged  along  the  sides  of  the 
body,  extending  from  the  posterior  end  to  the  level  of  the  cirrus  sac. 
The  follicles  are  more  numerous  and  closer  together  in  the  posterior 
region,  gradually  becoming  fewer  in  the  anterior  part  of  the  vitelline 
zone.  They  lie  just  above  the  limiting  membrane  which  forms  the 
dorsal  boundary  of  the  musculature  of  the  adhesive  disc,  and  number 
up  to  forty  on  each  side.  They  vary  in  size,  measuring  from  10  to  40/ia 
in  diameter.  In  some  specimens  they  appear  to  be  arranged  in  a  double 
row  on  each  side  with  the  follicles  placed  alternately,  but  there  is  com- 
mon and  wide  variation  from  this  condition.  Collecting  ducts  extend 
along  the  median  face  of  the  vitellaria  and  at  the  level  of  the  ootype 
pass  mediad  where  they  unite  to  form  a  small  receptacle  which  empties 
into  the  ootype.  In  C.  cokeri  the  vitelline  follicles  are  smaller  and  fewer 
in  number  than  in  C.  insignis. 

The  genital  pore  (Fig.  54)  is  double,  situated  in  the  median  line 
on  the  ventral  side  of  the  forebody,  dorsal  and  anterior  to  the  adhesive 
disc.  There  is  no  genital  atrium,  the  two  ducts  open  to  the  exterior 
separately,  the  opening  of  the  cirrus  sac  is  on  the  right  and  that  of  the 
metraterm  is  on  the  left.  Barker  and  Parsons  described  a  genital  atrium 
opening  thru  a  common  pore,  but  I  fail  to  find  such  a  structure.  In 
C.  insignis,  Osborn  described  a  single  genital  opening  and  a  genital 
atrium,  but  in  sections  of  C.  insignis  I  find  the  same  condition  as  in 
C  cokeri. 

Excretory  System. — Most  of  the  observations  on  this  system  were 
made  on  living  specimens.  As  the  water  evaporated  from  under  the 
coverglass  the  worm  was  flattened  and  the  larger  excretory  tubules 
could  be  easily  followed.  The  pore  (Fig.  50)  is  median,  dorsal,  near 
the  posterior  end  of  the  body.  There  may  or  may  not  be  a  small  papilla- 
like prominence  around  the  pore.     There  is  a  single  excretory  vesicle, 


54  ILLINOIS  BIOLOGICAL  MOSOGRAPHS  [334 

situated  between  the  large  flask  like  ends  of  the  collecting  ducts  and 
the  pore.  In  the  pulsations  of  this  organ,  the  anterior  ventral  part 
contracted  and  the  constriction  passed  posteriad  and  dorsad,  expelling  the 
fluid  thru  the  pore.  The  two  collecting  ducts  extend  cephalad  from  the 
excretory  vesicle,  one  on  either  side  of  the  forebody,  median  to  the  vitel- 
laria.  Just  posterior  to  the  pharj'nx  each  duct  divides,  sending  a  branch 
cephalad  on  the  lateral  side  of  the  pharynx  and  anterior  sucker,  and  a 
second  branch  turns  caudad.  This  caudal  branch  subdivides  into  a 
branch  leading  to  the  region  of  the  genital  pore,  and  a  longer  larger 
branch  which  passes  posteriorly  to  the  region  of  the  testis  and  receives 
many  smaller  side  branches.  Cross  sections  (Fig.  49)  show  the  collect- 
ing ducts  to  be  dorsal  in  position.  In  morphological  and  histological 
features  the  excretory  system  of  C.  cokeri  is  similar  to  that  of  C.  insig- 
nis.  Osborn  gives  a  comparison  of  the  excretory  system  in  that  species 
with  the  same  system  in  other  genera  of  the  family. 

Sensory  Structures. — There  is  a  dorsal  nerve  commissure  crossing 
the  anterior  part  of  the  pharynx,  and  nerves  were  traced  running  ceph- 
alad and  caudad  from  it.  In  about  half  of  the  specimens  mounted  in 
toto,  a  pair  of  black  pigment  spots  is  present  on  the  dorsal  commissure. 
In  others  only  a  single  spot  is  visible  and  in  a  few  specimens  none  could 
be  found.  In  all  the  sectioned  worms,  however,  both  "eye  spots"  were 
observed,  altho  in  some  they  were  very  small  and  diflScult  to  find.  These 
structures  are  dorsal  and  anterior  to  the  pharj-nx  (Fig.  58)  and  consist 
of  a  large  number  of  black  pigment  granules.  No  lens  is  present. 
Barker  and  Parsons  report  that  ej-e  spots  were  not  found. 

At  the  ends  of  the  cross  partitions  of  the  adhesive  disc  are  the  mar- 
ginal organs  (Fig.  55).  These  structures  occui*  in  the  interstices  be- 
tween the  muscular  ridges  of  the  ventral  disc  and  its  peripheral  wall. 
Such  an  organ  consists  of  a  fine  tube  about  20^  in  length  and  l/i  in  di- 
ameter, leading  dorsad  from  the  ventral  surface  of  the  ridge  and  termi- 
nating in  a  large  spherical  cavity  in  the  form  of  a  bulb.  The  entire  or- 
gan is  lined  with  cuticula,  continuous  with  that  of  the  external  surface 
of  the  body.  The  external  half  of  the  canal  possesses  a  thick  wall  com- 
posed of  annular  muscles,  while  the  internal  portion  has  a  thin  wall  with 
a  few  annular  fibers  and  is  often  curved  or  looped.  At  the  external  end 
of  the  inner  portion  there  is  a  flask-like  enlargement  which  is  connected 
with  the  heavy  waUed  region  by  a  short  constricted  portion  about  2,u  in 
length.  Longitudinal  fibers  pass  from  the  wall  of  the  distal  part  of  the 
canal  to  points  near  its  inner  end  or  to  the  wall  of  the  cavit}'.  This  lat- 
ter structure  is  spherical  or  oval  15  to  20/i  in  diameter,  and  emptj'  in 
most  of  the  sections.  It  has  a  fibro-membranous  wall  and  in  a  few  cases 
is  filled  with  homogenous  granular  substance  or  fluid.     In  other  sections 


335]  NORTH  AMERICAS  ASPIDOGASTRIDAE—STUNKARD  SS 

the  bulb  contains  a  few  granules  or  "concretionary  bodies",  but  in  struc- 
ture these  appear  identical  with  the  cuticular  lining  of  the  cavity.  As 
mentioned  above  the  organs  are  located  in  the  angles  between  the  muscu- 
lar ridges  and  the  wall  of  the  disc,  and  are  set  in  a  mass  of  non-staining 
fibrous  connective  tissue.  Some  of  the  fibers  pass  dorsad  from  the  bulb 
between  the  muscular  ridges  to  the  limiting  membrane  of  the  disc,  but 
in  appearance  these  are  similar  to  the  others  and  there  is  nothing  to  in- 
dicate that  they  are  nervous  in  character.  However  in  one  section, 
stained  with  Heidenhain  's  iron  haematoxylin,  there  is  a  nerve  fibril  pass- 
ing around  the  bulb  and  terminating  on  the  inner  end  of  the  heavy  walled 
portion  of  the  canal  (Fig.  55).  Other  nervous  structures  were  not  ob- 
served. The  connective  tissue  contains  manj^  nuclei,  similar  in  size  and 
shape,  and  in  no  case  was  a  connection  between  these  nuclei  and  the 
marginal  organ  observed.  No  glandular  cells  and  no  evidence  of  a  se- 
cretion were  found.  In  the  study  of  living  specimens  it  was  noted  that 
the  marginal  organs  were  everted  and  retracted  as  the  worm  moved. 
Everted  they  appeared  as  membranous  sacs  and  their  movement  was 
rapid  and  precise.  No  evidence  was  found  to  indicate  that  these  organs 
possess  a  glandular  function ;  the  character  of  their  movement  and  the 
nerve  fibril  leading  to  the  canal  as  demonstrated  incline  the  writer  to  re- 
gard these  structures  as  sensory. 

Similar  organs  have  been  reported  as  present  in  all  the  genera  of 
the  family  except  Stichocotyle.  They  were  first  noted  in  Aspidogaster 
by  Dujardin  (1845)  who  described  them  as  pores  or  orbicular  glands. 
Voeltzkow  (1888)  observed  in  Aspidogaster  that  they  were  protrusible 
and  retractile,  and  for  this  reason  decided  they  were  sensory.  Monti- 
celli  (1892)  described  them  in  Cotylogaster  michaelis  and  supported  the 
idea  of  their  sensory  character.  Nickerson  (1902)  described  in  Cotylo- 
gaster occidentalis  a  bundle  of  fibers  which  he  regarded  as  a  nerve  en- 
tering the  bulb  at  its  basal  end,  and  a  cluster  of  bipolar  nerve  cells  lying 
upon  the  side  of  the  bulb  against  which  the  canal  is  coiled  when  retracted. 
He  stated  that  the  presence  of  the  bipolar  cells  establishes  the  sensory 
character  of  these  organs.  He  described  the  bulb  as  filled  with  vesicular 
or  granular  material,  and  tho  no  nuclei  were  discernible,  regarded 
this  as  cytoplasm  of  granular  cells  in  different  stages  of  activity. 

Loess  (1902)  in  Lophotaspis  vallei  described  two  types  of  structures 
as  occurring  in  the  interstices  between  the  muscular  ridges  of  the  ventral 
disc.  Those  around  the  periphery  of  the  disc  at  the  ends  of  the  cross 
ridges  he  called  ' '  marginal  bodies ' '  and  those  at  the  intersections  of  the 
ridges  he  called  "tentacles."  The  first  he  compared  M'ith  the  marginal 
organs  of  other  aspidogastrid  genera,  and  the  tentacles  differ  only  slightly 
in  details  of  structure.     He  stated  there  was  nothing  in  the  structure 


56  ILLINOIS  BIOLOGICAL  MONOGRAPHS  [336 

of  the  marginal  bodies  to  warrant  the  former  belief  in  their  sensory 
character.  Granules  in  the  cavity  he  regarded  as  droplets  of  a  secretion ; 
and  in  the  connective  tissue  dorsal  to  the  cavity  he  described  sac-like 
spaces  with  fine  granular  contents,  and  he  found  also  nuclei  but  was  un- 
certain whether  they  lay  in  the  spaces  or  between  them.  The  marginal 
bodies  he  regarded  as  glandular  organs  altho  doubtful  as  to  their  exact 
function.  He  described  the  tentacles  as  having  a  spindle-shaped  cavity 
with  glandular  apparatus  around  the  inner  end,  and  a  canal  leading  from 
this  blind  end  to  the  limiting  membrane  which  formed  the  dorsal  wall  of 
the  musculature  of  the  adhesive  disc.  He  considered  these  structures  as 
adhesive  or  absorptive,  but  states  that  their  physiological  significance 
was  doubtful. 

Osborn  (1904)  in  C.  insignis  described  the  marginal  organs  as  con- 
sisting of  three  parts,  the  canal  with  its  muscular  wall,  the  cavity,  and  a 
dorsal  fibrous  part.  The  fibrous  part  he  regarded  "  as  a  trunk  of  nerve 
fibers  running  at  least  to  the  muscles  of  the  organ  and  perhaps  partly 
sensory  as  well."  The  central  cavity  possessed  "a  lining  of  moderate 
thickness  composed  of  cuticle  outwardly  but  of  nucleated  epithelium  on 
the  inner  side."  This  cavity  he  found  empty  or  with  one  or  more  "con- 
cretionary objects. ' '  He  says,  ' '  This  indicates  that  secretion  is  going  on 
the  products  being  removed  from  time  to  time.  I  think  the  muscles  de- 
scribed above  may  be  used  in  discharging  these  products,  the  longitudinal 
fibers  may  act  as  dilators  of  the  outlet,  needed  to  enable  such  large  ob- 
jects to  make  their  escape. ' '  Later  he  states,  "  I  do  not  find  in  Cotylaspis 
any  evidence  of  a  glandular  structure  in  the  fibrous  part,  and  do  con- 
sider the  bulbous  part  as  epithelial  and  secretory." 

The  marginal  organs  apparently  differ  somewhat  in  structure  in 
the  different  genera.  Of  all  the  authors.  Loess  alone  seems  to  have 
morphological  evidence  for  his  conclusion  that  in  Lophotaspis  they  are 
glandular  in  character.  The  statement  of  Osborn  that  in  Cotylaspis 
insigtiis  the  bulb  is  partly  lined  with  cuticula  and  partly  with  secretive 
epithelium,  I  regard  as  doubtful.  Certainly  in  my  sections  of  that  spe- 
cies (Fig.  56)  the  bulb  is  lined  with  cuticula  thruout.  In  the  dorsal  part 
of  the  cavity  shown  there  are  many  small  structures  but  they  appear  to 
be  composed  of  the  same  material  as  the  lining  cavity.  If  they  are  cutic- 
ular,  this  would  argue  against  the  glandular  character  of  the  organ  since 
in  its  functional  activity  the  material  wovild  be  swept  out  with  the  secre- 
tion instead  of  accumulating  and  forming  such  large  objects  as  he  shows 
in  his  figure.  Furthermore  it  would  be  almost  if  not  entirely  impossible 
for  such  large  bodies  to  pass  thru  the  small  canal  which  leads  to  the  ex- 
terior. These  "concretionary  objects"  are  apparently  the  only  basis 
for  Osborn 's  claim  that  the  organs  are  glandular  since  he  stated  that  he 


337]  NORTH  AMERICAN  ASPIDOGASTRIDAE—STUNKARD  57 

found  no  glandular  structure  in  the  fibrous  part.  Instead  of  supporting 
I  believe  that  they  are  subversive  to  the  idea  of  the  glandular  nature  of 
th«  organ. 

In  my  material  the  fibers  which  pass  dorsad  from  the  bulb  are  iden- 
tical in  appearance  with  the  adjacent  connective  tissue  and  do  not  ap- 
pear to  be  nervous.  The  muscular  wall  of  the  canal  is  I  believe,  used 
primarily  in  the  eversion  and  retraction  of  the  external  part  of  the  canal. 
In  living  specimens  under  observation  the  everted  part  of  the  marginal 
organ  was  about  the  size  and  shape  of  the  thick-walled  distal  portion  of 
the  canal,  and  this  is  probably  the  only  part  protrusible.  With  this  ever- 
sion, the  base  of  the  thick  walled  portion  to  which  the  nerve  is  distributed 
would  be  at  the  tip  of  the  everted  structure  in  a  position  to  function  in  a 
sensory  capacity. 

Comparisons. — This  is  the  third  aspidocotylean  described  from  tur- 
tles, the  two  previously  reported  forms  being  Cotylaspis  lenoiri  Poirier 
1886,  and  Lophotaspis  valid  Stossich  1899,  both  African  species.  Poirier 
described  C.  lenoiri  from  the  intestine  of  Tetrathyra  vaillanti  from  Sen- 
egal, and  Looss  (1902)  reports  it  as  occurring  also  inTrionyx  notilica  of 
the  Nile.  Lophostaspis  vallei  is  parasitic  in  the  stomach  of  Thalassochelys 
corticata.  Cotylaspis  cokeri  is  very  different  from  Lophotaspis,  but  shows 
considerable  resemblance  to  C.  lenoiri.  However,  a  comparison  of  the 
description  of  C.  lenoiri  with  specimens  of  C.  insignis  and  C.  cokeri  shows 
decided  difference  in  the  size  and  shape  of  the  worms  and  of  the  adhesive 
disc,  in  the  number  of  alveoli  and  marginal  organs,  in  the  sive  of  ovary 
and  testis,  of  cirrus  sac,  and  of  eggs.  The  three  forms  agree  in  essential 
morphological  features  and  fit  the  diagnosis  of  the  genus  Cotylaspis  as 
given  by  Leidy,  but  are  equally  clearly  good  species  in  that  genus. 

CLASSIFICATION  OF  THE  FAMILY 

The  last  classification  of  the  Aspidogastridae  was  made  by  Nickerson 
(1902).  Since  additions  and  changes  have  subsequently  been  made, 
further  revision  seems  advisable.  The  present  arrangement  is  largely 
based  on  the  work  of  Nickerson  and  brings  the  classification  to  date. 
Present  information  supports  the  validity  of  the  following  genera. 

I.  Aspidogaster  von  Baer  1827.  Type  species,  A.  conchicola  von 
Baer. 

Oval  adhesive  disc,  four  rows  of  alveoli,  marginal  organs  present, 
mouth  subterminal,  no  oral  sucker,  one  testis. 

This  genus  contains  A.  conchicola  which  infests  the  pericardium  and 
renal  organs  of  various  species  of  Unionidae  in  Europe  and  North  Amer- 
ica. It  is  also  found  in  gastropods  and  in  the  immature  condition  in 
th«  intestine  of  Unionidae.  Other  species  of  this  genus  are  A.  limacoides 


58  ILLINOIS  BIOLOGICAL  MONOGRAPHS  [338 

Diesing  1834  from  the  intestine  of  a  fish  (Leuciscus)  in  Europe,  a  form 
which  Stafford  (1896)  and  Kofoid  (1899)  suspect  of  being  identical  with 
A.  co-nchicola.  The  species  A.  macdonaldi  was  placed  in  this  genus  by 
Montieelli  (1892)  and  removed  to  Lophotaspis  by  Looss  (1902).  Linton 
(1905)  described  A.  ringens  from  the  intestine  of  Micropognon  undula- 
tus  and  Trachinotus  carolimis  at  Beaufort,  North  Carolina.  MacCallum 
and  MacCallum  (1913)  gave  a  more  complete  description  of  A.  ringens 
and  described  A.  kemostoma  n.  sp.,  both  from  the  intestine  of  Trachinotus 
carolinus. 

II.  Cotylaspis  Leidy  1857.      Type  species,  C.  insignis  Leidy. 
Oval  adhesive  disc,  three  rows  of  alveoli,  marginal  organs  present, 

mouth  subterminal,  no  oral  sucker,  one  testis. 

This  genvis  contains  the  species  C.  insignis,  C.  lenoiri,  and  C.  cokeri. 
C.  lenoiri  was  described  by  Poirier  (1886)  as  a  species  of  Aspidogaster. 
Montieelli  (1892)  created  a  new  genus  Platyaspis  to  contain  Poirier 's 
species,  evidently  overlooking  the  similarity  between  it  and  the  form  re- 
ported by  Leidy.  He  declined  to  accept  the  genus  Cotylaspis,  suggesting 
that  C.  insignis  was  a  species  of  Aspidogaster.  Braun  (1879-1893)  as- 
cribed the  species  to  Aspidogaster.  Kofoid  (1899)  established  the  val- 
idity of  Leidy 's  genus  but  contended  that  the  genus  Platyaspis  should  be 
retained  for  Poirier 's  species.  Nickerson  (1902)  argued  that  tlije  differ- 
ences between  the  African  and  American  species  are  not  of  generic  im- 
portance and  suppressed  the  genus  Platyaspis,  making  Aspidogaster 
lenoiri  Poirier  and  Platyaspis  lenoiri  (Poir.  1886)  Montieelli  1892,  syn- 
onomous  with  Cotylaspis  lenoiri  Poir.  Cotylaspis  insignis  occurs  ectopara- 
sitically  in  the  mantle  cavity  of  Unionidae  in  North  America ;  C.  lenoiri 
is  from  the  intestine  of  Tetrathyra  vaillanti  of  Africa;  and  C.  cokeri  is 
from  the  intestine  of  Malacoclemys  lesueurii  of  North  America. 

III.  Macraspis  Olsson  1868.  Type  species,  M.  elegans  Olsson. 

A  single  row  of  confluent  acetabula  in  adhesive  organ,  marginal  or- 
gans present,  mouth  terminal,  one  testis. 

The  single  species  is  parasitic  in  the  gall  bladder  of  Chimaera  mon- 
strosa,  a  fish  from  the  coast  of  Europe. 

IV.  Stiehocotyle  Cunningham  1884.  Type  species,  S.  nephropis 
Cunningham. 

A  single  row  of  more  or  less  distinct  acetabula,  marginal  organs  lack- 
ing, mouth  subterminal,  oral  sucker  absent,  two  testes. 

Cunningham's  original  description  was  of  the  larva  and  Montieelli 
(1892)  declined  to  recognize  its  generic  importance,  thinking  it  might 
be  a  form  of  Macraspis.  Odhner  (1898)  by  discovering  the  adult  and 
tracing  the  life  history,  established  the  genus.  Adults  live  in  the  bile 
ducts  of  the  liver  of  rays ;  larvae  occur  encysted  in  the  wall  of  the  intes- 


339]  NORTH  AMERICAN  ASPIDOGASTRIDAE—STUNKARD  59 

tine  of  the  larger  marine  Crustacea.  Cunningham  described  it  from  the 
Norwegian  lobster,  Nephrops,  and  Nickerson  (1895)  reported  it  from  the 
American  lobster,  Homarus  americanus. 

V.  Cotylogaster  Monticelli  1892.  Type  species,  C.  michaelis  Mon- 
ticelli. 

Adhesive  disc  with  three  rows  of  alveoli,  marginal  organs  present, 
mouth  terminal,  oral  sucker  present,  two  testes. 

Two  species  have  been  described ;  C.  michaelis  occurs  in  the  intestine 
of  Canthanis  vulgarus,  a  European  fish,  and  C.  occidentalis  Nickerson 
1899  is  parasitic  in  the  intestine  of  Aplodinotus  grunniens  of  North 
America. 

VI.  Lophotaspis  Looss  1902.  Type  species,  L.  vallei  (Stossich) 
1899. 

Adhesive  organ  with  four  rows  of  alveoli,  marginal  organs  present  at 
all  the  intersections  of  the  ridges  of  the  adhesive  disc,  cirrus  absent. 

Loos  in  1901  reported  L.  adhaerens  as  belonging  to  a  new  genus  of  the 
Aspidogastridae,  but  was  not  aware  that  Stossich  two  years  before  had 
described  the  same  form  as  Aspidogaster  vallei.  Looss  later  (1902)  de- 
scribed and  figured  the  form  under  the  name  of  Lophotaspis  vallei.  In  the 
same  paper  he  compared  A.  macdonaldi  with  L.  vallei  and  placed  the 
former  species  in  the  genus  Lophotaspis.  This  trematode  was  reported 
but  not  named  by  Macdonald  in  1878,  and  named  by  Monticelli  (1892) 
as  a  species  of  Aspidogaster.  Nickerson  (1902)  declared  it  to  be  an  as- 
pidogastrid,  but  different  from  all  other  known  species,  and  predicted  that 
a  new  genus  would  have  to  be  erected  for  it  when  its  structure  was  better 
known.  Macdonald  reported  one  hundred  eighty  extensile  structures, 
like  the  tentacles  of  a  snail,  occurring  at  the  margins  and  intersections 
of  the  ridges  of  the  adhesive  disc.  Nothing  is  known  of  the  internal 
structure.  Looss  in  placing  the  form  in  the  genus  Lophotaspis  stated : 
"Mit  ihrer  tentakeltragenden  Bauchscheibe  bildet  die  Art  aber  ganz 
zweifellos  einen  fremden  Eindringling  in  der  Gattung  Aspidogaster,  da 
dessen  typischen  Art  jedenfalls  solche  Tentakel  nicht  besitzt.  Qerade 
diesen  auffallended  Character  aber  teilt  sie  mit  Lophotaspis;  bin  ich 
geneigt,  A.  macdonaldi  Monticelli,  trotzdem  bei  ihm  die  Genitaloffnung 
weiter  riickwarts  liegt  als  bei  Lophotaspis  vallei,  aus  dem  genus  Aspido- 
gaster herauszunehmen  and  zu  Lophotaspis  zu  stellen." 


60  ILLINOIS  BIOLOGICAL  MONOGRAPHS  [340 


PARAMPHISTOMIDAE 

HISTORICAL.  REVIEW  OP  THE  FAMILY 

The  genus  Amphistoma  was  created  by  Rudolphi  (1801) ;  concerning 
it  Stiles  and  Hassall  (1908)  state,  "Rudolphi  deliberately  renamed  a 
previously  validly  named  genus,  namely  Strigea  Abildgaard,  1790,  re- 
ferring clearly  to  this  fact  both  in  1801a,  50-51,  and  1802b,  92.  He  makes 
but  one  combination  {Amphistoma  siibclavatum) ,  but  since  Amphistoma 
is  clearly  a  new  name  proposed  for  an  older  one  (Strigea),  which  Rud. 
changed  on  the  alleged  ground  that  it  was  inappropriate,  Amphistoma 
should  be  suppressed  in  favor  of  Strigea  and  take  the  same  species  as 
type." 

Fischoeder  (1903)  stated:  "In  Bezug  auf  den  Namen  Amphisto- 
mum  ^vill  ich  jedoch,  wie  schon  gesehen  (1901),  nochmals  darauf  hin- 
weisen,  dass  der  Name  Amphistoma  von  Rudolphi  (1801)  als  neue 
Bezeichnung  fiir  die  Gattung  Strigea  Abildg.  1790  eingefiihrtworden  ist. 
Der  Name  Amphistoma  kommt  daher  nach  dem  Prioritatsgesetz  als 
synonym  zu  Strigea  in  Fortfall.  Die  urspriingliche  einzige  und  also 
aueh  typische  Art  der  Gattung  Strigea  Abildg.  1790  (Amphistoma  Rud. 
1801)  M'ar  Planaria  strigis  Goeze  1782  Amphistoma  macrocephaliim  Rud. 
1809  Holostomum  macrocephalum  Nitsch.  1819) .  Wenn  daher  der  Name 
Strigea  wieder  zu  Geltung  wieder  bebracht  werden  soil,  so  darf  er  nur 
fiir  die  heutige  Gattung  Holostomum  weitergefiihrt  werden,  wahrend 
die  heutige  Gattung  Amphistomum  einen  anderen  Namen  erhalten 
muss.  Ich  habe  in:  Zool.  Anz.  1900,  V.  24,  p.  367  den  Namen 
Paramphistomum  vorgeschlagen  und,  die  Eintheilung  nach  dem  Fehlen 
Oder  Vorhandensein  der  Pharyngealtaschen  beibehaltend,  in  der  Fam. 
Paramphistomidae  Fischdr.  (Amphistomidae  Montic.  1888)  die  Unter- 
famUien  Paramphistominae  und  Cladorchinae  Fischdr.  unterschieden. 
In  diesen  beiden  Unterfamilien  lassen  sich  die  bekannten  Formen  unter- 
bringen. ' '  The  names  Paramphistomum  and  Paraphistomidae  have  been 
accepted  by  Liihe,  Looss,  Odhner,  and  other  writers  and  are  used  in  this 
paper. 

The  paramphistomes  of  mammals  were  the  first  forms  of  this  family 
discovered,  and  they  have  been  the  subjects  of  extensive  study  by  Fisch- 
oeder (1903)  and  Stiles  and  Goldberger  (1910) ;  a  number  of  species  are 
known. 


341]        NORTH  AMERICAN  PARAMPHISTOMIDAE—STUNKARD  61 

I  have  been  unable  to  find  any  record  of  work  done  on  the  param- 
phistomes  of  fish  between  that  of  Diesing  (1836)  and  MacCallum  (1905). 
Daday  (1907)  described  two  species  of  Diplodiscus,  two  species  of  a  new 
genus  he  called  Microrchis,  three  species  of  a  new  genus  named  Pseudo- 
cladorchis,  and  added  Amphistoma  oxycephalus  Dies,  with  two  new 
species  to  the  genus  Chiorchis.  He  included  a  section  on  the  anatomy 
and  histology  of  the  forms. 

The  only  paramphistomes  from  amphibians  are  four  species  of  Dip- 
lodiscus reported  from  frogs :  D.  subclavatus  from  the  frogs  of  Europe, 
D.  temperatus  from  those  of  North  America,  and  D.  megalochnis  and 
D.  microchrus  from  Australian  frogs. 

Information  concerning  paramphistomes  of  reptiles  is  very  scanty. 
Braun  (1901)  lists  three  species  from  turtles:  Amphistoma  grande  Dies- 
ing, A.  scleroporum  Creplin,  and  A.  sp.  Bellingham.  Bellingham  (1844) 
listed  Amphistoma  sp.  from  the  intestine  of  Chelonia  imbricata  but  gives 
no  description,  so  this  species  should  receive  no  further  consideration. 
Braun  (1901)  supplemented  the  description  of  Creplin  (1844)  by  a  brief 
report  of  the  single  specimen  of  A.  scleroporum  from  the  museum  at 
Greifswald,  but  the  worm  was  sexually  immature  and  consequently 
the  observations  were  limited.  A.  grande  was  collected  by  Natterer 
from  the  intestine  of  five  species  of  turtles  in  Brazil,  but  the  descrip- 
tion of  Diesing  is  confined  to  the  external  appearance  and  the  material 
may  have  comprised  more  than  one  species.  One  other  species  is  known 
from  turtles,  a  form  described  by  Looss  (1902)  as  A.  spinulosum  from 
the  intestine  of  Chelone  mydas.  The  description  of  Looss  is  very  com- 
plete but  because  of  the  scarcity  of  known  species  and  our  limited  knowl- 
edge of  the  group,  at  that  time  he  refrained  from  any  attempt  at  classi- 
fication. He  stated  that  the  species  is  probably  closely  related  to  A. 
scleroporum  and  A.  grande. 

In  addition  to  the  description  of  the  species,  Looss  (1902)  discussed 
the  question  of  the  oral  sucker  and  the  pharynx  in  the  group  and  com- 
piling evidence  from  comparative  anatomy  and  embryology,  he  argued 
that  the  anterior  sucker  of  the  amphistomes  should  be  regarded  as  homolo- 
gus  to  the  oral  sucker  of  the  distomes.  In  this  paper  also  he  described 
the  muscular  thickening  at  the  caudal  end  of  the  esophagus  as  a  pharynx 
and  described  a  peristaltic  contraction  of  the  organ  from  the  anterior 
to  the  posterior  end,  altho  in  an  earlier  paper  (1896)  he  had  stated  that 
the  esophageal  thickening  of  Gastrodiscus  was  not  a  true  muscular 
pharynx.  Concerning  this  latter  structure,  Odhner  (1911)  says,  "Ich 
verwende  diese  Bezeichnung,  weil  es  mir  doch  nicht  so  ganz  sicher 
erscheint,  dass  es  sieh  hier  um  ein  dem  gewohnlichen  Distomenpharynx 
homologes  Organ  handelt.    Auch  wenn  es  so  ware,  konnte  iibrigens  der 


62  ILLINOIS  BIOLOGICAL  MONOGRAPHS  [342 

ziemlieh  verschiedene  Bau  einen  besondern  Namen  rechtf ertigen ;  der 
Oesophagiis  miisste  aber  dann  konsequenterweise  als  Praphar\iix 
bezeichnet  werden."  In  his  later  paper  Looss  (1912)  referred  to  this 
organ  as  an  esophageal  bulb. 

The  arrangement  of  the  fibers  in  concentric  lamellae  and  the  func- 
tion of  the  organ,  acting  as  sphincter  instead  of  a  dilating  pumping  or- 
'  gan,  argue  against  its  homology  with  the  pharynx  of  the  distomes.  These 
conditions  I  found  myself  in  the  two  species  of  the  new  genus  Alasso- 
stoma.  However  in  the  other  of  my  new  forms,  Zygocotyle  ceratosa,  in 
stead  of  concentric  muscle  lamellae,  the  fibers  at  the  sides  of  the  lumen 
extend  radially.  A  thickening  of  the  esophageal  musculature  is  de- 
scribed for  Gastrodiscus,  Homalogaster,  Diplodiscus,  Microrchis,  Chior- 
chis,  Schizamphistoma,  Alassostoma,  and  Zygocotyle.  In  agreement  with 
Looss  (1912),  the  MTiter  regards  the  tube  leading  from  the  oral  sucker 
to  the  intestine  at  the  esophagus  and  the  muscular  thickening  of  the 
wall  of  the  esophagus  as  an  esophageal  bulb. 

In  this  same  paper  Looss  (1912)  reinvestigated  the  species  Amphis- 
toma  scleroporum  and  described  its  structure  in  detail.  Discussing  the 
taxonomy  of  the  species  he  says,  "Die  Frage  nach  den  Verwandtschaft- 
lichen  Bezeichnungen  des  Amp.  scleroporum  ist  insofern  leicht  beant- 
wortet,  als  seine  enge  Verwandtsehaft  zu  A.  spinulosum,  auf  die  ieh 
schon  friiher  vermutungsweise  hinwies  (1902b,  p.  437)  jetzt  offen  zutage 
tritt.  Ich  wiirde  nicht  zogern,  beide  Arten  in  dieselbe  Gattung  ein- 
zureihen,  wenn  nicht  gewisse,  wenn  auch  kleine  Differenzen  im  anatom- 
ischen  Baue  existierten  die  meiner  Auffassung  nach  innerhalb  von  wirk- 
lich  natvirlichen  Gattungen  nicht  vorkommen.  Diese  Differenzen  bes- 
tehen,  1.  in  dem  Fehlen  des  vor  dem  Mundsaugnapfe  gelegenden  starken 
Sphincters  von  A.  scleroporum  bei  A.  spinulosum;  2.  der  Eeduction  der 
Saugnapftaschen,  die  bei  A.  spinulosum  deutlich,  bei  A.  scleroporum 
nicht  nach  aussen  hervortreten ;  3.  dem  Fehlen  der  kleinen  Seitenzweige 
an  den  vordersten  Enden  der  Blasenschenkel  von  A.  scleroporum  bei 
A.  spinulosum;  4.  in  dem  etwas  abweichenden  Bau  der  Dotterstocke  (bei 
A.  scleroporum  in  der  Mitte  fast  zusammen  and  ohne  eigentliehe  quere 
Dottergange,  bei  A.  spinulosum  rein  seitlich  mit  langen  queren  Dotter- 
gangen) ;  5.  in  dem  etwas  verschiedenen  Verhalten  der  Lymphschlauche 
(ungemein  reiche  Verzweigung  im  Umkreise  der  Saugnapfe  bei  A. 
scleroporum,  kaum  angedeutete  Verzweigung  bei  A.  spi7iulosum) .  Bin 
ich  demnach  auf  Grande  dieser  Untersehiede  auch  iiberzeugt,  dass  in  den 
beiden  Arten  Eeprasentanten  je  eines  besondern  G^nus  vorliegen,  so 
geniigt  fiir  meinen  gegenwartigen  Zweck  doch  die  formelle  Aufstellung 
der  Gattung  Schizamphistomum  fiir  A.  scleroporum,  in  die  ich  A.  spinu- 
losum vorlaufig  provisorisch  einbeziehe.      Als  die  wesentlichen  Charak- 


343]        NORTH  AMERICAN  PARAMPHISTOMIDAE—STUNKARD  63 

tere  dieser  Gattung  oder  der  Unterfamilie,  zu  der  sie  sich  friiher  oder 
spater  auswachsen  wird,  betrachtet  ieh  den  Aufbau  der  Excretionblase 
aus  zwei  sehr  langen,  bis  ins  Kopfende  einfaclieii,  unter  sich  uicht  ver- 
bundenen  Schenkeln  und  den  Aufbau  des  Lymphgefasssystemes  aus 
jederseits  drei  in  der  Umgebung  der  Saugnapfe  verastelten  Schlauchen." 

He  might  well  have  added  to  his  list  of  differences  that  in  S.  spinu- 
losum  there  is  a  single  loop  of  the  excretory  vesicle  wound  dorsally 
over  the  cecum  of  each  side  while  in  S.  scleroporum  there  are  eight  loops 
winding  irregularly  around  the  cecum  of  each  side.  In  the  same  article 
(p.  355)  speaking  of  the  excretory  system  in  paramphistomes  of  mammals 
he  says  this  system  is  situated  deep  in  the  body  and  in  the  larger  groups 
is  a  stable  and  conservative  organsystem.  In  a  former  paper  Looss 
(1902  :837)  says,  "Zwisehen  der  Species  einer  natiirlichen  Gattung 
bestehen  anatomische  Unterschiede  nieht;  die  Speciescharaktere  werden 
dargesteUt  allein  durch  Differenzen  in  der  Grosse  des  Korpers  und  der 
einzelnen  Organe,  Hand  in  Hand  mit  denen  leichte  Veranderungen  ihrer 
Form,  ihrer  Lage  und  wenn  sie  reieher  gegliedert  oder  in  eine  Anzahl 
von  Theilstiicken  zerfallen  sind,  Aenderungen  in  der  Zahl  der  Glieder 
resp.  der  Theilstiicke  gehen  konnen."  As  a  matter  of  fact,  the  argument 
of  Looss  in  my  opinion  appears  to  show  clearly  that  S.  scleroporum  and 
S.  spinulosum  are  not  members  of  the  same  genus;  as  indeed  he  has  al- 
ready suggested  himself  that  in  future  researches  a  new  genus  will  have 
to  be  created  to  contain  S.  spinulosum. 

The  single  paramphistome  reported  from  snakes  was  described  ^by 
Cohn  (1903)  as  Amphistomum  dolichocotyle,  and  in  his  (1904)  classifi- 
cation of  the  Diplodiscinae  placed  in  the  genus  Catadiscus.  It  is  from 
the  intestine  of  Herpetodryas  fuscus. 

The  only  paramphistomes  previously  known  from  North  America 
are  Amphistoma  grande,  reported  by  Leidy  (1888)  from  the  intestine  of 
the  terrapin;  two  specimens  from  the  small  intestine  of  the  muskrat 
which  according  to  the  same  author,  "appear  to  belong  to  Amphistoma 
subtriqiietrum" ;  Diplodiscus  temperatus  Stafford  long  considered  iden- 
tical with  D.  suiclavatus  Dies. ;  and  Wardius  ziiethicus  Barker  and 
East,  from  the  cecum  of  Fiber  zibethicus.  The  reports  of  Leidy  contain 
no  description  except  the  length  of  the  worms.  Barker  and  East  suspect 
that  Leidy 's  specimens  from  the  muskrat  belong  to  their  new  genus  and 
species  Wardius  zibethicus;  and  it  is  not  unlikely  that  the  specimens  from 
the  terrapin  are  specifically  identical  with  those  described  here  as  Alasso- 
stoma  magnum  Stunkard  1916.  Neither  the  description  of  Stafford 
nor  that  of  Barker  and  East  contains  complete  anatomical  information. 
Stafford  distinguished  between  the  lymph  and  excretory  systems. 
Barker    and    East    make    no    mention    of    the    lymph    system;    they 


64  ILLINOIS  BIOLOGICAL  MONOGRAPHS  [344 

state  that  the  oral  sucker  is  wanting  and  describe  the  anterior  sucker  as 
the  pharynx,  notwithstanding  the  arguments  of  Pratt  (1900),  Looss 
(1902)  and  Stiles  and  Goldberger  (1910)  that  the  anterior  sucker  of  the 
amphistomes  is  homologous  with  the  oral  sucker  of  the  distomes. 

The  material  of  this  family  available  for  the  present  study  consisted 
of  representatives  of  two  species  from  North  American  turtles,  and  an- 
other species  from  the  duck,  Anas  platyrhynchos.  A  study  of  the  liter- 
ature showed  that  these  forms  could  not  be  included  in  any  previously 
described  genera. 

THE  GENUS  ALASSOSTOMA 

A  new  genus  Alassostoma  is  formed  to  include  the  two  species  from 
turtles.  The  genus  is  characterized  by  the  presence  of  large  oral  evag- 
inations  which  open  independently  into  the  oral  sucker,  an  esophageal 
bulb  composed  of  concentric  muscle  lamellae,  a  hermaphroditic  duct, 
germ  glands  near  the  middle  of  the  body  in  the  median  line,  both  testes 
anterior  to  the  ovary,  vitellaria  consisting  of  small  scattered  follicles  in 
the  lateral,  and  posteriorly  in  median  areas  of  the  body,  Laurer's  canal 
opening  in  the  mid-dorsal  line  anterior  to  the  opening  of  the  excretory 
vesicle.  Alassostoma  magnum  is  to  be  taken  as  type  of  the  genus,  and 
in  it  is  included  also  the  new  species  A.  parvum. 

The  genus  Alassostoma  has  the  type  of  lymph  and  excretory  systems 
present  in  the  genus  Schizamphistoma  and  designated  by  Looss  as  char- 
acteristic of  the  subfamily  to  which  that  genus  belongs.  Looss  (1912) 
predicted  that  with  the  discovery  of  other  forms  it  would  be  necessary 
to  create  a  new  subfamily  to  contain  them,  and  at  that  time  stated  the 
subfamily  characters.  With  the  discovery  of  a  second  genus,  so  similar 
to  Schizamphistoma  that  the  two  must  be  included  in  the  same  subfamily, 
the  formal  recognition  of  the  new  subfamily  is  necessary.  Schizamphis- 
toma Looss  was  designated  as  type  and  the  name  of  the  subfamily  be- 
comes Schizamphistominae.  The  subfamily  contains  the  genera  Schiz- 
amphistoma, including  also  S.  spinulosum  which  as  already  indicated  by 
Looss  and  discussed  in  this  paper  is  tj'pe  of  a  new  genus,  and  the  genus 
Alassostoma.  The  distinguishing  characters  of  the  subfamily  as  stated 
by  Looss  are  two  long  excretory  vesicles  which  extend  singly  to  the  an- 
terior end  of  the  body  and  a  lymph  system  composed  of  three  canals  on 
either  side  of  the  body  which  run  longitudinally  and  break  up  into  many 
sinuses  in  the  regions  of  the  suckers. 

Comparisons. — When  one  compares  the  species  A.  magnum,  and  A. 
parvum  with  descriptions  in  the  literature,  they  are  seen  to  agree  most 
closely  with  Schizamphistomum  scleroporum  and  S.  spinulosum  Looss. 


345]        NORTH  AMERICAN  PARAMPHISTOMIDAE—STUNKARD  65 

Mention  has  previously  been  made  of  the  anatomical  differences  existing 
between  these  species  and  a  statement  ventured  that  such  wide  and  fun- 
damental differences  should  not  be  present  in  a  natural  genus.  A.  mag- 
num agrees  with  S.  scleroporum  in  general  appearance  and  size,  in  type 
of  excretory  and  lymph  systems,  character  of  vitellaria,  and  in 
general  type  of  reproductive  and  alimentary  organs;  but  A.  mag- 
num has  large  oral  evaginations,  which  pockets  are  reduced  and  do  not 
extend  outside  the  sucker  in  S.  scleroporum,  and  A.  magnum  lacks  the 
preoral  sphincter  which  is  present  in  ;Si.  scleroporum.  In  A.  magnum 
the  uterus  and  cirrus  sac  open  to  the  surface  thru  a  common  hermaphro- 
ditic duct;  in  S.  scleroporum  they  open  separately.  Looss  (1899  :  551) 
says  one  of  the  most  important  of  generic  characters  is  the  structure  of 
the  copulatory  organs.  In  A.  magnum  the  testes  are  further  posteriad 
and  the  ovary  is  situated  one-fourth  to  one-third  of  the  body  length  from 
the  posterior  end  instead  of  at  the  level  of  the  anterior  margin  of  the 
acetabulum  as  is  the  case  in  S.  scleroporum.  In  S.  scleroporum  the  testes 
and  ovary  are  widely  separated  and  in  A.  magnum  they  are  compara- 
tively close  together.  These  differences  appear  to  be  of  sufficient  impor- 
tance to  exclude  the  American  species  from  the  genus  Schizamphistoma. 

A.  magnum  agrees  with  S.  spinulosum  in  the  presence  of  oral  evag- 
inations and  lack  of  preoral  sphincter,  but  differs  from  it  in  the  manner 
of  the  coiling  of  the  excretory  vesicles,  in  the  presence  of  a  common  herm- 
aphroditic duct  and  in  the  character  of  the  vitellaria,  as  well  as  the  rela- 
tive positions  of  the  testes  and  ovary.  The  morphological  facts  show 
differences  too  fundamental  to  permit  the  inclusion  of  both  these  species 
in  a  single  genus. 

Alassostoma  parvum  agrees  with  A.  magnum  in  general  morpho- 
logical features,  presence  of  oral  evaginations,,  lack  of  preoral 
sphincter,  type  of  lymph  and  secretory  systems,  character  of  geni- 
tal organs  and  ducts,  also  in  relative  position  of  testes  and  ovary.  A. 
parvum  therefore  agrees  with  and  differs  from  S.  scleroporum  and  S. 
spinulosum  in  the  same  manner  as  A.  mxignum.  That  the  two  forms  are 
not  different  developmental  stages  of  the  same  species  is  shown  by  the 
great  difference  in  the  size  of  the  worms  and  the  relative  differences  in 
the  size  of  suckers  and  genital  organs.  One  of  the  species  of  A.  magnum 
10  mm.  long  is  not  sexually  mature,  while  in  the  sectioned  specimen  of  A. 
parvum  which  is  less  that  3  mm.  long  spermatoza  were  present  in  the  tes- 
tes and  vas  deferens.  Further,  ova  were  present  in  the  oviduct,  and  tlie 
ootype  and  anterior  part  of  the  uterus  were  filled  with  spermatoza. 
Eggs  were  present  in  only  one  of  the  seven  specimens  of  A.  magnum  and 
the  absence  of  eggs  in  the  three  specimens  of  A.  parvum  does  not  signify 
that  it  is  a  young  stage  of  A.  mxignum.    A.  magnum  is  large  and  has 


66  ILLINOIS  BIOLOGICAL  MONOGRAPHS  [346 

small  suckers  and  A.  parvum  is  small  and  has  relatively  large  suckers, 
and  this  feature  suggested  the  name  Alassostoma. 

ALASSOSTOMA  MAGNUM  Stunkard  1916 
[Figures  59  to  65] 

The  material  of  this  species  consists  of  one  worm  from  Pseudemys 
troosti  from  Havana,  Illinois ;  one  from  P.  elegans  from  the  same  locality  ; 
two  from  P.  elegans  from  Chicago,  Illinois ;  and  three  specimens  from  an 
unknown  turtle  from  Marshall,  Missouri.  The  first  four  specimens  were 
collected  by  the  writer  from  the  large  intestine  near  its  juncture  with 
the  small  intestine,  and  the  material  from  Marshall,  Mo.,bears  the  label, 
"From  cloaca  of  turtle." 

In  the  preserved  state  the  worms  are  10  to  12  mm.  in  length,  3  to  5 
mm.  in  breadth,  and  1.5  to  2  mm.  in  thickness.  One  specimen  studied 
in  the  living  condition,  measured  18  mm.  in  length  when  fully  extended ; 
preserved  it  is  11  mm.  long,  3.8  mm.  wide  and  2  mm.  thick.  One  fixed 
specimen  10  mm.  long  and  3  mm.  wide  is  not  sexually  mature. 

In  the  living  state  the  worms  are  clear,  hyaline,  with  the  digestive 
ceca  visible  as  brown  lines.  Their  movements  are  very  slow.  In  shape 
(Fig.  59)  they  are  more  or  less  oval,  with  the  acetabulum  forming 
a  slight  caudal  projection.  The  acetabulum  is  slightly  sub-terminal,  cir- 
cular or  ovoid,  usually  wider  near  the  anterior  than  the  posterior  end. 
The  opening  is  necessarily  relatively  narrower  than  the  sucker  itself,  in 
one  specimen  the  opening  is  merely  a  slit,  1.4  mm.  long,  0.38  mm.  wide 
near  the  anterior  end  and  posteriorly  tapering  to  a  point.  In  the  largest 
specimens  the  acetabulum  is  2.5  mm.  long  by  2  mm.  wide,  and  in  the 
smallest  it  is  2  mm.  by  2  mm. 

The  cuticular  covering  of  the  body  is  unarmed,  and  measures  10  to 
12/i  in  thickness.  It  is  turned  in  at  the  openings  of  the  excretory  and 
reproductive  systems  and  lines  the  digestive  tract  to  the  bifurcation. 
The  dermo-muscular  wall  has  the  circular,  longitudinal,  and  oblique  layers 
well  developed  and  inside  the  oblique  layer  there  is  an  additional  layer 
of  longitudinal  fibers  (Pig.  60).  Dorso-ventral  fibers  are  scanty  or 
lacking  and  the  parenchyma  of  the  bodv  is  very  loose  and  vacuolated 
(Fig.  64). 

Alimentary  tract. — The  oral  sucker  is  terminal,  spherical  to  ovoid 
in  shape,  usually  longer  in  the  antero-posterior  axis  and  somewhat  wider 
anteriorly  than  posteriorly.  It  is  deeply  set  in  the  parenchyma  of  the 
body  and  measures  0.9  to  1.35  mm.  in  length  and  0.6  to  0.9  mm.  in  width. 
Radial  fibers  pass  from  the  external  limiting  membrane  to  the  cuticxda 
lining  the  sucker;  in  a  cross  section  thru  the  sucker  (Fig.  65),  the  inside 


347]        NORTH  AMERICAN  PARAMPHISTOMIDAE—STUNKARD  67 

two-thirds  of  the  outer  half  is  a  nuclear  zone  and  all  the  nuclei  are  col- 
lected in  this  area.  Half  way  between  the  nuclear  zone  and  the  lumen 
there  is  a  narrow  band  of  circular  fibers.  The  oral  evaginations  arise  at 
the  caudal  end  of  the  oral  sucker  by  two  separate  openings,  one  on  either 
side,  and  extend  dorsad  and  caudad.  They  are  0.35  to  0.6  mm.  long, 
flattened  dorso-ventrally,  0.15  to  0.2  mm.  in  width.  These  sacs  are  lined 
with  cuticula  and  their  wall  is  continuous  with  that  of  the  oral  sucker. 
Externally  there  is  a  layer  of  longitudinal  fibers  and  inside  this  sets  of 
annular  fibers  (Fig.  63).  Oblique  and  radial  fibers  are  occasionally  seen 
but  are  very  scanty. 

The  esophagus  is  0.6  to  1.3  mm.  in  length ;  it  is  lined  with  cuticida 
and  the  wall  contains  external  longitudinal  and  internal  annular  fibers. 
At  the  caudal  end  of  the  esophagus,  just  anterior  to  the  bifurcation  of 
the  alimentary  tract,  there  is  a  prominent  esophageal  bulb.  It  varies 
from  0.65  to  0.95  mm.  in  length  and  from  0.33  to  0.5  mm.  in  width;  it 
is  formed  by  a  thickening  of  the  annular  fibers  of  the  wall  of  the  esoph-  ' 
agus.  A  cross  section  is  represented  in  Figure  60  and  shows  the  eighteen 
concentric  lamellae  of  muscles.  No  nuclei  are  present  in  these  annular 
muscles.  Both  the  oral  evaginations  and  the  esophagus  are  surrounded 
by  clusters  of  deeply  staining  cells  (Fig.  63).  Looss  (1896)  described 
similar  cells  in  Gastrodiscus  and  believed  they  secrete  the  lining  of  the 
esophagus.  The  ceca  are  flattened  laterally  and  are  of  very  unequal 
caliber,  small  lateral  evaginations  occur  on  opposite  sides  at  the  same 
level  recalling  the  condition  in  some  of  the  Turbellaria.  The  diverticula 
extend  almost  to  the  acetablum,  about  0.37  mm.  intervening.  They  have 
a  muscular  coat  consisting  of  external  annular  and  internal  longitudinal 
fibers  and  an  epithelial  lining  of  columnar  cells  which  show  faint  long- 
itudinal striations  (Fig.  62). 

Male  Reproductive  Organs. — The  testes  are  slightly  lobed,  oval, 
longer  in  the  transverse  diameter,  and  vary  in  size  from  0.27  by  0.35  mm. 
to  0.45  by  0.9  mm.  They  are  situated  one  behind  the  other  or  in  con- 
tracted specimens  slightly  on  opposite  sides  of  the  median  line.  They 
are  approximately  the  same  size  in  any  one  specimen  and  are  separated 
by  about  the  length  of  one  of  the  testes,  tho  in  contracted  specimens  they 
may  lie  closer  together.  The  vasa  efferentia  arise  from  the  dorsal  anter- 
ior margins,  the  duct  from  the  posterior  testis  on  the  left  and  the  duct 
from  the  anterior  testis  on  the  right  side  of  the  body.  They  pass  dorsad 
and  cephalad,  and  0.4  to  0.5  mm.  caudad  of  the  bifurcation  of  the  diges- 
tive tract  they  unite  to  form  a  much  coiled  seminal  vesicle,  which  near 
the  pore  passes  into  a  small,  poorly  developed  cirrus  sac.  In  sectioned 
individuals  it  could  be  seen  that  the  seminal  vesicle  was  filled  with  sper- 
matoza.    In  one  specimen  the  coils  of  the  vesicle  extend  thru  twenty 


68  ILLINOIS  BIOLOGICAL  MONOGRAPHS  (348 

cross  sections  each  15/i  in  thiqlmess,  and  the  tube  is  so  coiled  that  in  a 
section  of  the  worm  there  are  ten  or  fifteen  sections  of  the  vesicle.  In  an- 
other individual  cut  in  frontal  sections  the  seminal  vesicle  extends  antero- 
posteriorly  thru  0.57  mm.  The  prostate  gland  is  enclosed  by  the  cirrus 
sac  and  fills  the  entire  region  between  the  wall  and  the  central  canal. 
The  cells  are  more  numerous  in  the  posterior  part  of  the  sac,  gradually 
becoming  fewer  in  the  anterior  region.  The  sac  is  approximately  0.37 
mm.  long  and  0.185  mm.  in  diameter.  It  is  dorsal  on  the  right  side  of 
the  body,  and  the  terminal  end  of  the  uterus  is  ventral  on  the  left  side 
of  the  body. 

Female  Reproductive  Organs. — The  ovary  is  spherical  or  oval,  0.275 
to  0.35  mm.  in  length  and  0.33  to  0.57  mm.  in  width,  in  or  near  the  me- 
dian line,  about  the  width  of  the  caudal  testis  behind  the  latter.  The 
oviduct  is  very  small  and  arises  from  the  dorsal  margin  of  the  ovary  (Fig. 
61).  After  a  coil  posteriad  Laurer's  canal  is  given  off  and  passes  in  a 
winding  course  to  the  dorsal  surface.  There  is  no  receptaculum  seminis. 
Just  after  the  origin  of  Laurer's  canal,  the  oviduct  passes  into  ilehlis' 
gland,  where  the  vitelline  duct  is  received.  There  is  no  vitelline  re- 
ceptacle in  either  of  the  sectioned  worms,  but  the  right  and  left  ducts  are 
very  large.  They  meet  in  the  median  line  posterior  and  ventral  to 
Mehlis'  gland,  and  a  duct  passes  to  the  ootype.  The  uterus  coils  an- 
teriad,  either  between  or  around  the  testes  and  opens  thru  the  hermaphro- 
ditic duct  to  the  genital  pore. 

The  genital  pore  is  in  the  median  line  ventral  to  the  esophageal  bulb, 
and  there  is  a  small  genital  sinus.  The  cirrus  sac  and  metraterraal  por- 
tion of  the  uterus  open  to  the  exterior  thru  a  common  hermaphroditic 
duct  (Fig.  60). 

The  viteUaria  consist  of  smaU  irregularly  shaped  follicles,  lying  al- 
most entirely  in  the  ventral  half  of  the  body  and  extending  from  the  re- 
gion of  the  cephalic  testis  to  the  caudal  ends  of  the  ceca.  Anteriorly 
they  are  extracecal,  but  posteriorly  they  extend  into  the  intracecal  area ; 
near  the  ends  of  the  ceca  about  half  of  the  follicles  are  between  the  di- 
verticida. 

Eggs  were  present  in  only  one  specimen.  Here  there  were  three; 
they  measured  0.1  by  0.13  mm. 

Lymph  System. — This  system  consists  of  three  canals  passing  long- 
itudinally on  either  side  of  the  body,  one  lateral  and  two  mesal  of  each 
cecum.  Of  the  median  pair,  one  is  dorsal  and  the  other  ventral  (Fig. 
59).  These  canals  are  not  straight  but  wind  about  and  give  off  branches 
at  various  points.  These  branches  subdivide  in  turn  and  at  the  ends  the 
main  trunk  breaks  up  into  numerous  smaller  branches  so  that  the  entire 
body  is  penetrated  by  ramifications  of  this  system.     The  ceca,  the  genital 


349]        NORTH  AMERICAN  PARAMPHISTOMIDAE—STUNKARD  69 

organs,  and  the  suckers  are  especially  well  supplied  with  lymph  sinuses. 
Excretory  System. — The  excretory  pore  is  in  the  median  line  on  the 
dorsal  surface,  near  the  posterior  end  of  the  body,  and  the  median  termi- 
nal vesicle  extends  internally  and  anteriorly.  It  gives  off  a  brancli  to 
either  side  and  these  branches  of  the  collecting  vesicle  pass  anteriad, 
winding  about  the  cecum  of  either  side  in  many  loops  or  coils.  In  sections 
(Fig.  64)  the  tube  may  appear  on  either  side,  above,  or  below  the  cecum; 
in  a  single  section  it  may  be  cut  in  two  or  three  places  or  a  loop  may  puss 
half  to  two-thirds  of  the  way  around  the  cecum.  No  connections  between 
the  collecting  ducts  of  the  two  sides  could  be  seen,  and  they  were  traced 
to  the  region  of  the  oral  sucker. 

ALASSOSTOMA  PARVUM  Stunkard  1916 

[Figures  66  to  71] 

Three  individuals  of  this  species  were  collected  from  the  cloaca  of 
a  single  specimen  of  Chelydra  serpentina  from  Urbana,  Illinois.  One 
was  retained  as  an  alcoholic  specimen,  one  was  stained  and  mounted  as 
a  toto  preparation,  and  the  third  was  cut  into  cross  sections. 

The  worms  (Fig.  66)  are  thick  with  almost  parallel  sides,  rounded  at 
the  posterior  end  and  tapering  slightly  anteriorly.  Just  in  front  of  the 
acetabulum  the  body  narrows  slightly  and  then  widens  posteriorly  due 
to  the  presence  of  two  lateral  prominences  or  evaginations,  one  on  either 
side  at  the  level  of  the  anterior  part  of  the  acetabulum.  The  worms  are 
2.8  to  3  mm.  long  and  0.78  to  0.08  mm.  wide,  the  points  of  greatest  width 
are  at  the  level  of  the  testes  and  thru  the  posterior  lateral  prominences. 
The  sectioned  worm  is  0.8  mm.  in  width  and  0.54  mm.  in  thickness.  The 
acetabulum  is  subterminal,  oval,  0.8  mm.  in  length  and  0.7  mm.  in  width 
in  the  toto  preparation.  The  inside  measurements  of  the  same  sucker 
are  0.56  mm.  in  length  by  0.4  mm.  in  width  and  the  opening  is  0.45  mm. 
in  length  and  0.21  mm.  in  greatest  width. 

Alimentary  Tract. — The  oral  sucker  is  terminal,  ovoid,  0.46  mm. 
long  by  0.37  mm.  wide,  and  in  the  sectioned  worm  0.32  mm.  in  depth. 
In  the  mounted  specimen  tlie  sucker  is  widest  posteriorly,  and  from  the 
posterior  dorsal  part  on  either  side  there  is  an  oral  evagination.  These 
arise  separately  and  are  0.055  mm.  long.  Among  the  fibers  of  the  oral 
sucker  there  are  many  nuclei;  they  are  situated  in  the  peripheral  half 
of  the  sucker  and  are  confined  to  the  central  two-thirds  of  the  external 
half.  There  are  also  among  the  muscle  fibers  glandular  cells  with  ducts 
to  the  lumen  of  the  sucker.  The  esophagus  is  somewhat  coiled  but  ex- 
tends thru  0.2  mm.  and  is  surrounded  by  large  deeply  staining  gland 
cells.  The  posterior  part  is  enlarged  by  the  thickening  of  the  annular 
muscles  of  the  wall  which  forms  the  esophageal  bulb  (Fig.  70).     This 


70  ILLINOIS  BIOLOGICAL  MONOGRAPHS  [350 

structure  comprises  twelve  concentric  rings  or  lamellae  of  muscles.  It 
is  0.2  mm.  long  by  0.14  ram.  wide  in  the  toto  specimen  and  0.314  mm.  in 
depth  in  the  sectioned  individual.  The  diverticula  extend  posteriad  al- 
most to  the  cephalic  margin  of  the  acetabulum.  In  sections  they  are  oval, 
and  flattened  laterally.  In  the  intestine  of  the  sectioned  worm  there  are 
masses  of  small  nuclei,  possibly  from  the  epithelial  lining  of  the  cloaca 
of  the  host. 

Male  Reproductive  Organs. — The  testes  are  oval,  in  the  toto  speci- 
men they  are  0.17  mm.  long  by  0.17  mm.  wide,  and  in  the  sectioned  worm 
0.17  mm.  wide  by  0.29  ram.  thick.  They  are  situated  one  in  front  of  the 
other  in  the  median  line  and  in  the  ventral  part  of  the  body.  They  are 
close  together,  separated  only  by  a  thin  fibrous  sheet.  The  vasa  eileren- 
tia  arise  at  the  dorsal  margins  of  the  testes;  the  duct  from  the  caudal 
testis  pass  anteriad  and  anterior  to  the  cephalic  testis  unites  with  the 
duct  from  this  latter  testis.  The  vas  deferens  immediately  expands  into 
a  long  much-coiled  seminal  vesicle  whieli  passes  anteriad  and  into  the 
cirrus  sac  (Fig.  69).  Inside  the  cirrus  sac  the  tube  continues  in  large 
coils;  the  terminal  part  is  surrounded  by  the  cells  of  the  prostate  gland 
and  opens  to  the  surface  thru  a  short  hermaphroditic  duct.  There  is  a 
small  genital  papilla  (Fig.  71). 

Female  Reproductive  Organs. — The  ovary  is  oval ;  in  the  toto  speci- 
men it  is  0.098  mm.  long  and  0.088  mm.  wide,  and  in  the  sectioned  worm 
it  is  0.95  mra.  wide  and  0.134  mm.  thick.  It  is  median  in  position  and 
situated  midway  between  anterior  and  posterior  ends  of  the  body.  The 
oviduct  arises  at  the  dorsal  posterior  margin  and  passes  dorsad  and  pos- 
teriad' into  Melilis'  gland.  This  gland  is  large  and  well  developed. 
Here  Laurer's  canal  is  given  off  and  passes  in  short  coils  to  the  dorsal 
surface.  Just  after  the  origin  of  Laurer's  canal  a  short  common  vitelline 
duct  opens  into  the  ootype  and  the  oviduct  passes  ventrad.  It  expands 
to  form  the  initial  part  of  the  uterus,  turns  anteriad,  and  is  filled  witJi 
masses  of  spermatoza.  The  expanded  portion  of  the  iiterus  extends  an- 
teriad half  the  distance  to  the  caudal  testis  and  then  the  tube  contracts, 
passes  dorsad  and  in  a  winding  course  over  the  testes.  Anterior  to  the 
testes  it  turns  ventrad  and  enters  the  hermaphroditic  duct  on  the  pos- 
terior ventral  side.  The  vitellaria  extend  from  the  region  of  the  testes 
to  the  caudal  ends  of  the  digestive  ceca  and  consist  of  scattered  lobes, 
mostly  ventral  in  position.  Anteriorly  they  are  extracecal  but  behind 
the  ovary  they  are  intracecal  as  well. 

No  eggs  were  present  in  any  of  the  specimens. 

The  genital  pore  is  in  the  midventral  line,  just  posteror  to  the  bi- 
furcation of  the  alimentary  tract.  There  is  a  genital  sinus  but  no  geni- 
tal sucker. 


351]        NORTH  AMERICAN  PARAMPHISTOMIDAE—STUNKARD  71 

Lymph  System. — The  lymph  system  is  similar  to  that  described  for 
A.  magnum  and  consists  of  the  three  longitudinal  canals  on  either  side 
of  the  body,  one  canal  lateral  to  each  cecum  and  a  pair,  one  dorsal  and 
the  other  ventral,  mesal  to  the  diverticulum  of  either  side.  The  secon- 
dary branchings  could  not  be  traced  but  lymph  sinuses  are  present  in  sec- 
tions in  all  parts  of  the  body,  and  those  around  the  acetabulum  are  shown 
in  Figure  68. 

Excretory  System. — The  excretory  pore  is  median,  dorsal,  at  the 
level  of  the  cephalic  margin  of  the  acetabulum.  A  short  median  vesicle 
passes  ventrad  and  anteriad  and  divides  into  two  collecting  vesicles  as  in 
A.  magnum.  These  pass  ventrad  and  posteriad,  one  on  either  side,  loop 
around  the  caudal  ends  of  the  diverticula,  and  then  turn  anteriad,  wind- 
ing around  the  ceca  in  many  irregular  coils  so  that  in  sections  they  ap- 
pear lateral,  mesal,  ventral  or  dorsal  to  the  intestine;  often  the  tube  is 
cut  two  or  three  times  in  the  same  section  or  a  single  section  may  show 
a  coil  encircling  the  cecum  for  half  or  more  of  its  circumference  (Fig. 
67).  Anterior  to  the  bifurcation  of  the  alimentary  tract  the  ducts  con- 
tinue in  the  lateral  areas  of  the  body  and  can  be  traced  almost  to  the  oral 
sucker. 

THE   GENUS   ZYGOCOTYLE 

The  only  known  form  with  which  the  paramphistomes  from  the  duck 
can  be  compared  is  Amphistoma  lunatum.  This  species  was  described 
by  Diesing  (1836) ;  the  material  had  been  collected  by  Natterer  in  Brazil, 
South  America,  from  the  cecum  of  Anas  melanotus,  A.  ipecutiri,  A. 
'tnoschata,  Himantopus  wUsonii,  and  also  from  the  cecum  of  Cervus 
dichotomus.  Fishoeder  secured  the  original  specimens  from  the  Vienna 
museum  and  (1903)  gave  a  more  extended  description  of  the  form,  altho 
his  study  was  restricted  to  the  examination  of  toto  preparations.  He 
stated  that  the  citation  of  Cervus  dichotomus  as  a  host  of  this  form  is 
probably  an  error,  and  the  same  suspicion  had  been  mentioned  by  Diesing 
(1850).  It  is  at  once  apparent  that  the  present  species  is  very  similar 
to  A.  lunatum.  Both  are  parasites  of  American  ducks,  and  are  the  only 
paramphistomes  at  present  known  from  avian  hosts.  They  are  nearly 
equal  in  size,  are  similar  in  shape,  have  a  subterminal  oral  sucker,  re- 
productive systems  that  compare  very  closely,  digestive  tracts  similar 
in  character,  and  acetabula  of  the  same  form  consisting  of  an  anterior 
section  and  a  posterior  overhanging  lip  which  terminates  on  either  side 
in  a  small  cone-like  projection. 

Amphistoma  lunatum  has  been  placed  as  an  appendix  to  every  classi- 
fication of  the  paramphistomes  that  has  ever  been  attempted.  With  the 
discovery  of  a  form  so  similar,  the  two  must  belong  together  and  a 
new  genus  is  proposed  to  contain  the  two  species.    The  peculiar  divided 


72  ILLINOIS  BIOLOGICAL  MOXOGRAPHS  [352 

condition  of  the  acetabulum  suggested  the  name  Zygocotylo  as  appropriate 
for  this  genus.  Zygocotyle  ceratosa  has  been  designated  as  tj-pe  and  in 
the  genus  is  included  also  the  species  Amphistoma  lunatum. 

As  diagnostic  characters  of  the  genus  Zygocotyle  may  be  mentioned 
the  subterminal  oral  sucker,  the  posterior  sucker  divided  or  provided 
with  caudal  overhanging  lip,  absence  of  cirrus  sac  and  separate  openings 
of  the  male  and  female  ducts.  Others  Avill  undoubtedly  appear  when 
the  character  of  the  excretory  and  lymph  systems  are  known.  The  genus 
Zygocotyle  differs  from  all  other  known  genera  of  the  Paramphistomidae 
in  the  ventral  position  of  the  oral  sucker  and  the  peculiar  character  of 
the  acetabulum.  It  differs  from  the  Gastrodiscinae  in  the  shape  of  body 
and  absence  of  ventral  papillae,  and  from  the  Gastrothylacinae  in  the  ab- 
sence of  the  ventral  pouch.  In  the  lobed  testes  and  absence  of  cirrus 
sac  it  agrees  with  the  Paramphistominae,  but  the  oral  evaginations  ex- 
clude it  from  that  group.  The  absence  of  cirrus  sac  and  the  lobed  form 
of  the  testes  will  not  permit  its  inclusion  with  the  Cladorehinae.  The 
characters  of  the  Diplodiscinae  are  so  poorly  defined  that  a  comparison 
is  unsatisfactory ;  in  this  group  however,  a  cirrus  sac  is  present  and  both 
suckers  are  terminal.  As  none  of  the  existing  subfamilies  will  include 
the  genus,  a  new  subfamily  will  probably  have  to  be  made  to  contain  it. 
Since  the  present  classification  of  the  Paramphistomidae  is  somewhat  un- 
certain, and  the  structure  of  the  excretory  and  lymph  systems  of  this 
genus  are  as  yet  unknown,  no  further  attempt  at  classification  of  the 
group  is  made  at  this  time. 

ZYGOCOTYLE  CERATOSA  Stunkard  1916 
[Figures  72  to  79] 

The  material  of  this  species  consists  of  eight  specimens  from  the  in- 
testine of  Anas  platyrhynchos  from  Rock  County,  Nebraska.  The  intes- 
tine of  the  duck  had  been  cut  open  in  places  and  together  with  its  con- 
,tents  preserved  in  formalin.  The  fixation  of  the  parasites  is  so  poor 
,that  the  excretory  and  lymph  system  can  not  be  traced,  altho  remnants 
of  both  appear  in  sections. 

These  worms  (Fig.  72)  vary  in  length  from  3  to  6  mm.  and  in  width 
from  1.45  to  2.14  mm.  In  dorsal  or  ventral  aspect  they  are  elongate  oval 
jn  shape  with  the  acetabulum  forming  a  small  terminal  projection.  The 
cross  section  is  a  flattened  oval  and  toward  the  ends  of  the  body  becomes 
more  circular.  The  acetabulum  is  subterminal  and  consists  of  two  parts 
(Fig.  77),  an  anterior  part  extending  dorsally  and  anteriorl.v  into  the 
body  and  a  posterior  overhanging  lip  which  terminates  on  either  side 
in  a  little  horn  or  conical  projection  0.12  to  0.2  mm.  in  length.      The 


353]        NORTH  AMERICAN  PARAMPHISTOMIDAE—STUNKARD  IZ 

.cephalic  part  extends  anteriad  about  0.46  mm.  from  the  anterior  margin 
pf  the  opening  of  the  sucker.  The  opening  of  the  acetabulum  is  oval 
approximately  1.1  mm.  in  length  and  0.74  mm.  in  diameter.  The  sep- 
tum or  partition  which  divides  the  sucker  extends  almost  to  the  opening 
^nd  appears  to  separate  an  anterior  circular  part  from  the  remaining 
portion  but  there  is  a  single  oval  opening  of  the  acetabulum. 

The  euticula  is  unarmed,  slightly  thicker  on  the  dorsal  surface.  On 
the  ventral  surface  it  is  about  12/x  in  thickness  and  reaches  30/ti  in  thick- 
ness on  the  dorsal  surface.  It  is  not  homogeneous,  but  is  traversed  by 
fine  crinkled  lines  extending  from  internal  to  external  surfaces,  which 
give  it  a  reticulated  appearance.  The  entire  dorsal  surface  of  the  body 
is  underlaid  with  large  gland  cells  filled  with  a  substance  staining  deeply 
with  haematoxylin ;  and  their  ducts  lead  to  the  dorsal  surface.  The  con- 
tents of  the  gland  cells  and  their  duets  have  the  same  appearance  and 
staining  reaction  as  the  euticula  of  the  external  surface.  The  dermo- 
piuseular  sac  consists  of  the  usual  circular,  longitudinal,  and  oblique 
layers,  the  circular  layer  is  next  to  the  euticula.  From  the  body  wall 
there  are  many  large  dorso-ventral  muscle  strands  extending  thru  the 
body. 

Alimentary  Tract. — The  oral  sucker  is  subterminal,  circular  or 
slightly  oval  in  shape,  0.37  to  0.53  mm.  in  diameter.  The  oral  evagina- 
tions  are  0.15  to  0.22  mm.  in  length  and  0.07  to  0.1  mm.  broad ;  they 
branch  one  on  either  side  from  a  common  sinus  (Fig.  74)  which  opens 
into  the  dorsal  side  of  the  posterior  part  of  the  oral  sucker.  The  esoph- 
agus leads  from  the  oral  sucker  to  the  intestine ;  it  is  0.05  to  0.37  mm. 
in  length  and  is  surrounded  by  a  layer  of  deeply  staining  cells.  Its 
caudal  portion  is  surrounded  by  an  esophageal  bulb.  This  structure  is 
oval,  0.2  to  0.45  mm.  in  length,  0.18  to  0.23  mm.  in  width,  and  0.35  mm. 
in  thickness  in  the  specimen  cut  in  cross  sections.  It  is  situated  obliquely 
in  the  body,  the  anterior  end  is  ventral  and  the  posterior  end  more  dorsal 
in  position.  The  muscles  are  not  arranged  in  concentric  lamellae  as  in 
the  previously  described  paramphistomes ;  there  is  a  capsule  of  external 
longitudinal  fibers  and  the  body  of  the  organ  is  composed  of  fibers  ex- 
tending on  the  sides  from  the  central  canal  to  the  external  capsule  and 
above  and  below  the  canal  the  fibers  extend  across  from  the  lateral  walls 
of  the  bulb  (Fig.  73).  The  alimentary  tract  is  lined  with  euticula  to 
the  bifurcation.  The  ceca  are  flattened  laterally  and  the  lateral  walls 
are  sinuous  giving  them  a  very  irregular  appearance.  They  have  a  mus- 
cular wall  composed  of  outer  circular  and  inner  longitudinal  fibers  and 
extend  almost  to  the  opening  of  the  acetabulum,  about  0.1  to  0.15  mm. 
intervening.     They  terminate  just  caudad  of  the  excretory  pore. 

Male  Reproductive  Organs. — The  testes  lie  one  behind  the  other  in 


74  ILLIXOIS  BIOLOGICAL  MONOGRAPHS  [3S4 

the  median  line,  the  caudal  testis  is  almost  in  the  center  of  the  body,  and 
the  cephalic  testis  is  about  0.2  mm.  in  front  of  it.  They  are  about  the 
same  size,  lobulated,  oval,  crosswise  of  the  body,  almost  touching  the 
cecum  of  either  side.  They  are  ventral  in  position,  almost  touching  the 
ventral  body  wall  and  not  extending  far  into  the  dorsal  half  of  the  worm. 
They  vary  in  size  from  0.2  by  0.3  mm.  in  the  smallest  to  0.55  by  0.78  mm. 
in  the  largest  specimen.  The  vasa  efferentia  arise  from  the  anterior 
dorsal  margins,  the  right  tube  from  the  anterior  and  the  left  tube  from 
the  posterior  testis.  Near  the  genital  pore  they  unite  and  form  a  much 
coiled  seminal  vesicle  which  has  a  thickened  muscular  wall.  This  struc- 
ture extends  thru  twenty-five  cross  sections  cut  lO/i  thick.  The  termi- 
nal part  that  leads  ventrad  to  the  genital  pore  is  expanded,  the  walls  are 
thinner,  and  this  part  is  surrounded  by  the  cells  of  prostate  gland.  A 
cirrus  sac  is  absent,  the  male  and  female  tubes  open  to  the  exterior  in- 
dependently at  the  apex  of  a  slight  ventral  prominence.  The  opening 
of  the  male  duct  is  immediately  anterior  to  that  of  the  female  (Fig.  78). 

Female  Reproductive  Organs. — The  ovary  is  oval,  lobulated,  cross- 
wise of  the  body,  about  the  shorter  diameter  of  the  testis  behind  that  or- 
gan. In  the  smallest  specimens  it  is  0.2  by  0.33  mm.  and  in  the  largest 
0.33  by  0.52  mm.  The  oviduct  arises  at  the  dorsal  margin  as  a  very  small 
tube  and  passes  dorsad  where  Laurer's  canal  is  given  off.  This  canal 
winds  in  short  curves  to  the  dorsal  surface,  opening  anterior  to  the  ex- 
cretorj'  pore  (Fig.  79).  After  the  origin  of  Laurer's  canal  the  oviduct 
passes  posteriad  and  ventrad  into  Mehlis'  gland  where  a  short  common 
vitelline  duct  is  received.  The  uterus  then  coils  irregularly  in  close  folds 
to  the  genital  pore.  The  uterine  coils  are  largely  in  the  dorsal  part  of 
the  worm  altho  they  may  extend  into  the  ventral  portion  and  coil  around 
the  testes.  Laterally  the  coils  of  the  uterus  are  limited  by  the  ceca.  The 
terminal  part  has  a  slight  thickening  of  the  wall  but  not  a  distinct  de- 
limited metraterm.  The  vitellaria  are  well  developed,  large  follicles  ex- 
tending in  the  extracecal  areas  from  the  level  of  the  pasterior  edge  of 
the  oral  sucker  to  the  anterior  margin  of  the  opening  of  the  acetabulum. 
They  are  limited  medially  by  the  ceca  and  laterally  extend  almost  to  the 
body  wall.     They  are  more  ventral  than  dorsal  in  position. 

Eggs  are  present  in  large  numbers.  In  size  they  average  0.14  by 
0.083  mm. 

Comparison. — Zygocotyle  ceratosa  agrees  with  Z.  lunata  in  length, 
width,  and  size  of  oral  sucker,  but  in  the  former  species  the  oral  evagi- 
nations  are  smaller,  the  esophagus  is  much  shorter,  the  testes  and  ovary 
are  oval  and  lobed  instead  of  circular,  and  the  ceca  do  not  extend  to  the 
opening  of  the  acetabulum.  In  Z.  ceratosa  the  acetabulum  is  nearer  the 
ovary,  and  the  vitellaria  are  entirely  extracecal  while  in  Z.  lunata  they 
extend  between  the  ceca. 


355]       NORTH  AMERICAN.  PARAMPHISTOMIDAE—STUNKARD  75 

CLASSIFICATION  OP  THE  FAMILT 

Our  present  classification  of  the  Paramphistomidae  is  largely  the 
result  of  the  work  of  Monticelli,  Otto,  Fischoeder,  Cohn.  Daday,  .Stiles 
and  Goldberger,  Looss,  and  Odhner. 

The  first  division  of  the  group  was  made  by  Monticelli  (1892) 
when  he  separated  Gastrodiseus  from  the  rest  and  created  the  subfamily 
Gastrodiseinae.  Fischoeder  in  a  series  of  papers  described  several  spe- 
cies from  mammals,  and  formulated  (1903)  the  second  scheme  of  classi- 
fication. He  created  two  subfamilies :  Paramphistominae  in  which  the 
testes  are  lobed,  and  paired  oral  evaginations  and  cirrus  sac  are  absent ; 
and  Cladorehinae  characterized  by  branched  testes  and  the  presence  of 
paired  oral  evaginations  and  cirrus  sac.  Recent  additions  to  our  knowl- 
edge of  the  family  have,  however,  rendered  it  difficult  to  use  these  dis- 
tinctions satisfactorily.  Cohn  (1904)  created  the  subfamily  Diplodisc- 
inae  to  contain  the  genera  Diplodiscus,  Opisthodiscus,  and  Catadiscus. 
He  characterized  the  subfamily  as  follows:  "Amphistomiden  von  ged- 
rungener,  konischer  Form  und  runden  Querschnitt.  Mundsaugnapf  gut 
ausgebildet,  mit  zwei  retrodorsal  Tasehen.  Ein  grosser  Endsaugnapf, 
iiber  welchem  dorsal  der  Excretionsporus  liegt.  Mundoffnung  termi- 
nal, Darmschenkel  bis  zu  Endsaugnapf  reichend,  relativ  sehr  breit. 
Leben  im  Enddarm  von  Amphibien  und  Reptilien."  The  characteriza- 
tion is  inadequate,  since  the  anatomical  features  are  shared  by  almost 
half  the  members  of  the  family,  and  obviously  further  study  of  this 
group  is  necessary  to  establish  its  validity  and  determine  its  true  diag- 
nostic features. 

Stiles  and  Goldberger  (1910)  proposed  a  new  classification  of  the 
group.  They  created  a  new  superfamily  Paramphistomoidea  to  contain 
the  forms  previously  classed  as  amphistomes.  They  removed  Gastrodis- 
eus Leuck.,  and  Homalogaster  Poir.  from  Fischoeder 's  subfamily  Clad- 
orehinae and  created  a  new  family  Gastrodiscidae  to  contain  these  gen- 
era. They  created  another  new  family  Gastrothylacidae  to  contain  the 
general  Gastrothylax,  "Wellmanius,  Carmyerius,  and  Fisehoederius.  The 
family  Paramphistomidae  and  the  two  cited  above  comprise  the  three 
families  in  the  superfamily  Paramphistomoidea.  Stiles  and  Goldberger 
also  created  a  new  subfamily  Stephanopharynginae  to  contain  the  genus 
Stephanopharynx,  and  added  the  new  genus  Cotylophoron  to  the  sub- 
family Paramphistominae.  They  recognize  further  the  subfamily  Dip- 
lodiscinae  Cohn  and  list  the  four  subfamilies  Paramphistominae,  Cla- 
dorehinae, Diplodiscinae,  and  Stephanopharynginae  in  the  family  Par- 
amphistomidae. They  placed  Balanorchis  in  the  subfamily  Cladorehinae 
notwithstanding  Fischoeder 's  statement  that  such  an  arrangement  could 
not  be  considered. 


76  ILLINOIS  BIOLOGICAL  MONOGRAPHS  [356 

Braun  (1911)  reviewing  the  article,  objects  to  the  rank  of  superfam- 
ily  for  the  paramphistomes  and  says  placing  them  on  an  equality  of  rank 
^vith  the  Faseioloidea  is  not  justifiable. 

The  work  of  Stiles  and  Goldberger  is  criticized  at  the  hands  of 
Odhner  (1911)  as  follows:  "Dies  alles  zeigt  nun  evident,  wie  wenig 
Verstandnis  die  betreffenden  Autoren  fiir  die  moderne  natiirliche 
Digenensystematik  haben Mir  scheint  nun  diese  "Argu- 
mentation" ebenso  wie  viel  anders  (die  neue  topographische  Terminol- 

ogie)  in -derselben  arbeit  sehr  "unwise"  zu  sein die  Amphistomen 

entsprechen  im  systematischen  Range  einer  einzelnen  Distomenfamilie 
und  nicht,  wie  Stiles  and  Goldberger  gelaubt  haben,  der  Summe  samt- 
licher  dieser  Familien." 

Looss  (1912)  also  gives  a  critical  review  of  the  paper:  Die  Charak- 
terisierung  der  Arten,  Gattungen  usw.  baut  sich  auf,  einerseits  auf  eine 
pedantisch  ins  einzelne  gehende  Analyse  und  Beschreibung  der  Korper- 
form  und  der  Topographic  von  Darm  und  Genitalapparat,  anderseits 
auf  eine  konsequente  Ignorierung  der  beiden  Tatsachen,  dass  die  Tiere, 
als  Organismen,  innerhalb  gewisser  Grenzen  natiirlich  variieren,  und 
dass  Korperform  sowohl  wie  Topographic  der  Organs  mit  dem  Wachstum 
gesetzmassige,  mit  der  Kontraktion  a  priori  nicht  bestimmbare  Verander- 
ungen  erleiden.  Der  Aufbau  von  Lymph — und  Excretionsapparat 
bleibt  voUig  unberucksiehtigt.  Dass  die  Amphistomen  ein  "Lymphge- 
fasssystem"  iibcrbaupt  besitzen,  scheint  den  Autoren  unbekannt  zu 
sein. " 

The  classification  of  Stiles  and  Goldberger  as  pointed  out  by  other 
authors  is  based  on  superficial  characters  and  the  elevation  in  rank  of 
the  family  and  groups  within  the  family  is  in  most  cases  unwarranted. 
However,  the  subfamily  Gastrothylacinae  of  these  authors  appears  to  be 
clearly  distinguished  by  the  presence  of  the  large  ventral  pouch,  and  in 
my  opinion  should  be  retained. 

Looss  (1912)  considers  the  lymph  and  excretory  systems  of  major 
importance  in  classification.  As  characters  of  the  new  subfamily  Schiz- 
amphistominae  he  mentioned  the  type  of  IjTnph  and  excretory  systems. 
Since  the  lymph  system  has  not  yet  been  described  in  other  subfamilies, 
the  former  diagnoses  based  on  body  form,  types  of  digestive  and  repro- 
ductive systems,  presence  of  ventral  pouch,  etc.,  must  be  retained  for  the 
present.  Moreover,  since  so  many  of  the  forms  are  incompletely  de- 
scribed, and  considerable  difference  of  opinion  exists  in  regard  to  the 
taxonomic  value  of  the  different  features,  the  classification  of  the  group 
is  still  uncertain.  As  Looss  (1912)  says,  "Jeder  Klassifikationversuch, 
der  der  bau  von  Excretions — und  Lymphgefasssystem  ausser  acht  lasst, 
mag  sich  wohl  einen  Klassifikationsversuch  nennen,  kann  aber  niemals 


357]       NORTH  AMERICAN  PARAMPHJSTOMIDAE—STUNKARD  77 

Anspruch  darauf  eriieben,  als  naturlicher  oder  (was  dasselbe  ist) 
wissenseliaftlicher  Klassifikationsversuch  anerkannt  zu  werden. ' '  In  the 
same  article  he  states  that  for  many  years  he  has  been  engaged  in  prepar- 
ing a  revision  of  the  amphistomes  but  has  not  yet  completed  the  work 
which  will  present  a  classification  based  on  the  structure  of  the  lymph 
and  excretory  systems  and  the  copulatory  apparatus. 

The  only  arrangements  of  the  genera  of  the  family  that  have  been 
made  heretofore  are  those  of  Fishoeder  and  of  Stiles  and  Goldberger. 
The  classification  of  Fischoeder  does  not  appear  adequate  and  that  of 
Stiles  and  Goldberger  is  far  from  satisfactory,  but  for  sake  of  complete- 
ness both  are  appended  in  outline. 

Classification  of  Fischoeder  (1903) 
Paramphistomidae 

Paramphistominae 
Paramphistomum 
Gastrothylax 
Stephanopharynx 

Species  inquirendae,    A.  gigantocotyle 
A.  explanatum 
Cladorchinae 
Cladorchis 
Gastrodiscus 
Homalogaster 
Diplodiscus 
Chiorchis 

Species  inquirendae;  A.  liawkesi,  A.  collinsi,  A.  oma- 
tum,  A.  papUlatum,  A.  tuberculatum,  A.  emarginatum, 
and  A  lunatum. 
(Subfamily  nov.) 
Balanorchis 

Classification  of  Stiles  and  Goldberger  (1910) 
Paramphistomoidae 
Gastrodiscidae 

Gastrodiscus  ' 

Homalogaster 
Gastrothylacidae 

Gastrothylacinae 
Gastrothylax 
Wellmanius 
Carmyerius 
Fischoederius 


78  ILLINOIS  BIOLOGICAL  MONOGRAPHS  [358 

Paramphistomidae 

Paramphistominae 

Paramphistomum 

Cotylophoron 
Cladorchinae 

Cladorchis 

Taxorchis 

Chiorchis 

Microrchis 

Pseudocladorchis 

Pseudodiseus 

Balanorchis 

"Watsonius 

Pfenderios 
Diplodiscinae 

Diplodiscus 

Catadiscus 

Opisthodiscus 
Stephanopharynginae 

Stephanopharj-nx 

As  a  result  of  my  studies  on  this  family,  certain  data  have  been 
added  and  some  doubtful  points  cleared  up.  The  discovery  of  the  two 
species  of  the  new  genus  Alassostoma  and  the  demonstration  of  their  po- 
sition as  members  of  a  new  genus  in  the  subfamily  Schizamphistominae 
Looss  establishes  that  group.  The  description  of  the  new  genus  and 
species  Zygocotyle  ceratosa  throws  considerable  light  on  the  previously 
isolated  and  obscure  species  A.  lunatum  Dies.  In  conclusion  I  present 
a  tentative  revision  of  the  paramphistomes.  In  the  main  it  is  my  inter- 
pretation of  the  status  of  the  group  and  its  subdivisions.  The  new  genera 
of  Stiles  and  Goldberger  are  included  without  comment  altho  certain  au- 
thors do  not  recognize  their  validity.  I  have  had  no  opportunity  to  work 
on  this  material  and  consequently  any  judgment  on  my  part  must  appear 
unwarranted-  Because  of  the  scarcity  of  known  forms  and  the  incom- 
pleteness of  most  of  the  descriptions  it  is  impossible  to  present  a  final 
classification.  The  following  arrangement  is  provisional  and  likely  to 
be  replaced  whenever  a  natural  system  can  be  formulated  for  the  family. 

Paramphistomidae  Fischoeder  1901 
Gastrodiscinae  MonticeUi  1892 
Gastrodiscus 
Homalogaster 
Paramphistominae  Fischoeder  1901 


359]       NORTH  AMERICAN  PARAMPHISTOMIDAE—STUNKARD  79 

Paramphistomum 

Stephanopharynx  . 

Cotylophoron 
Cladorchinae  Fischoeder  1901 

Cladorchis 

Taxorchis 

Chiorchis 

Pseudodiscus 

Microrchis 

Pseudocladorchis 

Watsonius 

Pfenderius 
Diplodiscinae  Cohn  1904 

Diplodiscus 

Opisthodiscus 

Catadiscus 
Gastrothylacinae  Stiles  and  Goldberger  1910 

Gastrothylax 

Wellmanius 

Carmyerius 

Fischoederius 
Schizamphistominae  Looss  1912 

Schizamphistomum 

(Gen.  7WV.)  spinulosum 

Alassostoma 

Genera  of  uncertain  position 
(new  subfamily)  Fischoeder  1903 

Balanorchis 

-(new  subfamily)  see  text  p.  71 


Zygocotyle 


80  ILLINOIS  BIOLOGICAL  MONOGRAPHS  [360 


RELATION  OF  THE  FAMILIES  TO  THE  ORDER 

The  trematodes  are  generally  regarded  as  descended  from  a  tur- 
bellarian-like  ancestor  which  possessed  a  posterior  sucker.  "With  the 
assumption  of  the  parasitic  habit  adaptations  began  in  various  directions. 
The  ectoparasitic  forms  retained  many  of  their  former  characters  while 
the  added  protection  and  food  supply  afforded  those  specializing  toward 
endoparasitic  existence  provided  for  perpetuation  and  distribution  of 
the  species  thru  the  excessive  development  of  the  reproductive  apparatus. 
The  development  of  the  ectoparasitic  forms  is  simple  and  direct  while 
that  of  most  if  not  all  endoparasites  has  been  complicated  by  the  inter- 
polation of  one  or  even  more  secondary  or  intermediate  hosts. 

The  differences  in  type  of  adhesive  apparatus  may  in  a  general  way 
be  explained  thru  differences  in  habit.  The  oral  sucker  has  developed 
thru  continued  adhesion  by  the  anterior  end  in  maintaining  position,  in 
locomotion,  and  in  securing  food.  In  the  Gasterostomidae  the  mouth  is 
on  the  ventral  surface  and  an  independent  anterior  sucker  is  developed, 
altho  this  is  undoubtedly  a  secondary  feature,  as  in  the  cereariae  of  these 
forms  there  is  a  single  anterior  oral  sucker.  In  response  to  the  constant 
necessity  for  strong  adhesion  the  ectoparasitic  species  have  developed 
accessory  posterior  organs  of  attachment,  while  in  most  of  the  endopara- 
sitic forms  the  acetabulum  has  migrated  anteriad  or  disappeared  entirely. 

The  general  classification  of  MonticeUi,  which  is  followed  in  this 
paper,  is  based  primarily  on  the  character  of  the  adhesive  apparatus. 
In  the  Heterocotylea  the  posterior  sucker  has  been  replaced  by  a  disc 
which  bears  suckers  and  hooks ;  in  the  Aspidocotylea  the  acetabulum  has 
become  specialized  into  a  multiloculate  adhesive  organ ;  and  in  the  Mal- 
acocotylea  the  acetabulum  may  be  retained  in  its  primitive  terminal  posi- 
tion, or  it  may  have  migrated  anteriorly,  in  certain  cases  being  reduced 
and  in  others  disappearing  entirelj'.  In  the  young  individuals  of  many 
forms  in  each  of  the  three  groups  there  is  a  single  posterior  sucker  and 
this  fact  adds  weight  to  the  theory  that  the  present  groups  are  descended 
from  a  primitive  form  with  a  simple  posterior  sucker.  In  the  young 
stages  of  aU  the  Aspidogastridae  there  is  a  simple  posterior  sucker  and 
the  worm  closely  resembles  a  young  distome.  In  the  early  stages  of  the 
Heterocotylea  the  reversion  to  the  ancestral  conditions  is  not  so  complete, 
and  specialization  in  this  group  shows  clearly  that  it  is  widely  separated 


361]        NORTH  AMERICAN  PARAMPHISTOMIDAE—STUKKARD  81 

from  the  other  two  suborders  which  thru  the  presence  of  similar  young 
forms  appear  to  be  more  closely  related. 

The  morphological  structure  and  direct  development  of  the  Polys- 
tomidae  at  once  places  them  with  the  Heterocotylea.  In  the  adoption 
of  an  endoparasitic  mode  of  life,  however,  thy  show  a  distinct  departure 
from  the  other  members  of  the  suborder.  The  present  study  of  the 
Polystomidae  has  emphasized  the  unusual  morphological  variation  and 
wide  geographic  distribution  which  exists  in  the  family.  This  may  mean 
either  that  the  family  is  very  old  and  has  been  subjected  to  conditions 
producing  wide  variation,  or  that  the  group  really  lacks  family  entity 
and  consists  of  various  heterocotylean  forms  which  have  specialized  in 
the  direction  of  an  endoparasitic  habit  and  that  the  morphological  re- 
semblance is  eenogenetic. 

Pratt  (1908)  reviews  the  literature  and  arguments  for  convergent 
development  which  are  based  on  trematode'  morphology.  Johnston 
(1914)  argues  for  divergence  as  the  true  explanation  of  the  variation  of 
the  species  of  Pneumoeneces,  Gorgoderinae,  Brachycoelinae,  etc.,  and 
believes  that  the  elucidation  of  trematode  phylogeny  may  be  sought  in 
the  study  of  the  relationships  between  the  distribution  of  trematode 
parasites  and  the  distribution  of  their  hosts.  No  doubt  the  likenesses 
and  differences  in  the  structure  of  present  species  are  the  result  of  both 
convergence  and  divergence;  yet  it  seems  that  the  distributional  factor 
emphasized  by  Johnston  is  not  of  major  importance.  Parasitic  distri- 
bution could  precede  the  distribution  of  the  primary  and  secondary  hosts 
only  in  ease  the  parasites  changed  to  new  primary  or  secondary  hosts. 
Bdt  today  more  than  one  species  may  serve  as  primary  or  secondary 
host;  the  parasite  is  probably  in  a  restricted  degree  able  to  adapt  its 
life  history  physiologically  so  other  species  may  serve  as  hosts,  and 
primitively  this  adaptability  may  have  been  greater  than  now.  The 
distribution  of  the  parasites  certainly  depends  to  a  large  extent  on  the 
distribution  of  the  primary  host,  and  to  a  less  extent  on  the  distribution 
of  the  secondary  host,  but  the  presence  of  two  similar  parasites  in  the 
same  region  does  not  prove  that  their  hosts  had  primitively  the  same 
or  different  parasites.  The  life  history  of  the  trematodes  is  so  imper- 
fectly known  that  at  present  no  final  decision  can  be  made  on  this  basis. 

The  wide  variation  in  structure  of  the  members  of  the  genus  Poly- 
stoma  can  not  be  adequately  explained  thru  migration,  or  thru  differ- 
ences in  the  age  of  the  parasite,  type  of  host,  or  location  in  the  host.  In 
the  genus  so  far  as  is  known,  the  long  uterus  containing  many  eggs  is 
confined  to  species  infesting  the  urinary  bladder  of  amphibian  hosts  of 
the  Old  World.  However  in  respect  to  other  characters,  e.  g.,  the  shape 
of  the  caudal  disc  and  absence  of  great  hooks,  these  amphibian  forms  of 


82  ILLINOIS  BIOLOGICAL  MONOGRAPHS  [362 

the  Eastern  hemisphere  disagree  with  each  other  and  agree  with  forms 
parasitic  in  the  urinary  bladder  and  oral  cavity  of  North  American 
turtles.  The  turtle  parasites  have  a  very  similar  structure,  whether 
parasitic  in  the  urinary  bladder  or  in  the  pharyngeal  cavity.  Further- 
more, if  the  observations  of  Zeller  are  correct  and  the  individuals  of 
P.  integerrimum  becoming  mature  on  the  giUs  of  tadpoles  lack  external 
vaginae  and  have  a  spherical  testis  and  a  single  egg  in  the  uterus,  one  is 
entirely  at  a  loss  to  explain  the  variation  existing  in  the  genus. 

In  the  Aspidogastridae  the  young  individuals  have  an  oral  sucker 
and  a  small  posterior  acetabulum  without  dividing  ridges,  and  very 
closely  resemble  young  distomes.  The  mode  of  infection  is  almost  en- 
tirely unknown,  and  this  offers  a  promising  field  for  investigation.  The 
discovery  of  the  sexual  form  of  Stiehocotyle  by  Odhner  (1898)  estab- 
lishes the  fact  that  at  least  one  species  of  the  Aspidogastridae  has  an 
intermediate  host.  Nicfeerson  (1895)  observes,  "Owing  to  the  well 
known  tendency  of  fresh  water  conditions  to  obliterate  larval  life,  it  may 
well  be  that  Aspidogaster  has  secondarily  lost  a  more  or  less  compli- 
cated series  of  changes,  which  have  been  retained  by  its  relatives  inhabit- 
ing salt  water."  The  presence  within  the  family  of  both  direct  and 
indirect  development,  together  with  other  characters  common  to  both 
the  Heterocotylea  and  Malacocotylea  designate  it  as  an  intermediate 
group.  The  morphological  structure  is  similar  to  that  of  the  Mala- 
cocotylea while  the  manner  of  development  is  similar  to  that  of  the 
Heterocotylea.  Whether  the  Aspidogastridae  are  primitive  forms  or 
are  secondarily  degenerate  is  as  yet  undecided.  The  simple  and  archaic 
character  of  the  intestine,  the  eye  spots,  the  direct  development  and  the 
ectoparasitic  habit  as  it  occurs  in  the  family,  together  with  the  para- 
sitic infection  of  molluscs  by  adult  forms  strongly  suggests  a  very  primi- 
tive and  ancient  group.  It  is  probable  that  complete  evidence  concern- 
ing the  structure  and  life  history  of  this  family  would  go  a  long  way 
toward  solving  the  problem  of  whether  the  invertebrate  or  the  vertebrate 
is  the  original  host  and  the  attendant  problem  of  the  origin  of  double 
hosts. 

The  Paramphistomidae  appear  to  be  a  primitive  family  of  the 
Malacocotylea  that  have  retained  the  original  caudal  sucker,  altho 
certain  species  show  specializations  of  the  organ  from  the  simple  spher- 
ical type.  Considerable  light  is  thrown  on  the  relationships  of  the 
Malacocotylea  by  the  recent  work  of  Odhner  on  a  natural  system  for  the 
digenetic  trematodes.  He  strongly  advocates  the  view  that  the  mono- 
stomes  are  a  group  which  have  no  family  entity,  and  consist  of  individual 
forms  derived  from  various  distome  groups  which  have  alike  lost  the 
acetabulum.    Pointing  out  close  and  fundamental  agreement  in  internal 


363]        NORTH  AMERICAN  PARAMPHISTOMIDAE—STUNKARD  83 

structure  he  argues  that  the  monostome  family  Angiodictyidae  is  really 
a  subfamily  of  the  Paramphistomidae.  He  shows  essential  morphological 
agreement  between  Distoma  quadrangulum  Daday  and  the  fish  amphis- 
tomes.  His  examination  of  the  original  specimen  of  Aspidocotyle  con- 
firms the  statement  of  Braun  (1879-1893)  that  this  form  belongs  to  the 
amphistomes,  altho  its  relation  to  the  other  members  of  the  group  is 
uncertain.  Further  he  states  that  the  Gasterostomidae  by  the  structure 
of  the  cerearia  as  shown  in  the  oral  sucker  and  the  presence  and  relations 
of  the  oral  evaginations,  doubtless  belongs  to  the  Paramphistomidae. 
His  derivation  of  the  gasterostomes  thus  from  amphistome-like  forms  of 
frogs  is  plausible  since  the  frogs  serve  as  food  for  the  hosts  of  the 
gasterostomes.  To  Odhner's  argument  may  be  added  that  the  divided 
condition  of  the  body  in  Gastrodiscus  recalls  the  similar  condition  in 
certain  Aspidogastridae  and  suggests  a  possible  relationship  between 
these  forms.  The  morphological  comparisons  of  Odhner  and  other 
writers  appear  to  show  very  clearly  that  divergence  and  convergence 
have  both  had  great  influence  on  the  phylogeny  of  certain  trematode 
families. 


M  ILLINOIS  BIOLOGICAL  MONOGRAPHS  [364 


LIST  OF  NEW  SPECIES 

PAGE 

Alassostoma  magnum 66 

Alassostoma  parvum  69 

Polystoma  megacotyle  37 

Poly  stoma  microcotyle  39 

Polystoma  opacum _ _ 34 

Polystoma  orhiculare  31 

Zygocotyle   ceratosa  _  72 

A  preliminary  description  was  given  in  the  Journal  of  Parasitology, 
3:21-27. 


365]  NORTH  AMERICAN  POLY STOMIDAE— STUN KARD  85 


BIBLIOGRAPHY 
Andre,  J. 

1910.  Zur  Morphologie  des  Nervensystetns  von  Polystomum  integerriinum 
Froel.    Zeit  f.  wiss.  Zool.,  95:191-202,  11  figs. 

1910a.  Die  Augen  von  Polystomum  integerriinum  Froel.    Zeit  f.  wiss.  ZooL, 
95:203-220,  13  figs. 
Baeb,  K.  E. 

1827.     Beitrage    zur    Kenntniss    der    niedern    Thiere.     Nov.  act.  acad.  nat. 
cur.,  13,  pt.  2,  pp.  524-762.    (Cited  after  Braun  1879-93.) 
Barker,  F.  D. 

1915.    Parasites  of  the  American  Muskrat    Jour.  Paras.,  i  :i84-i98,  2  pi. 
Barker,  F.  D.,  and  Parsons,  S. 

1914.    A  New  Aspidobothrid  Trematode   from  Lesseur's  Terrapin.     Trans. 
Amer.  Micr.  Soc,  33 :26i-262. 
Beauchamp,  p.  de 

1913.    Polystomum   alluaudi,  n.   sp.     Voy.   de   Ch.   Alluaud   et   R.   Jeannel, 
Resultats  Scientific,  Memoirs  1913,  3  figs. 
Bellingham,  O. 

1844.    Cat^ogue  of  Irish  Entozoa,  with  Observations.    Ann.  and  Mag.  Nat. 
Hist,  13:340. 

BeNEBEN,    p.  J.  VAN 

1858.    Memoire   sur   les   vers   intestinaux.     Compt.   rend.   Acad.   Sci.   Paris, 
Suppl.,  2:1-376,  27  pi. 
Beneden,  p.  J.  VAN,  et  Hesse,  C.  E. 

1863.    Recherches  sur  les  Bdellodes  et  les  Trematodes  marins.     Arch.  roy. 
Belgique,   34:1-150,    15  pi. 
Benham,  W.  B. 

1901.    The    Platyhelmia,    Mesozoa,    and    Nemertini.      Treatise    on    Zoology 
(Lankester),  pt.  4. 
Blainville,  M. 

1828.    Vers.  Diet.  d.  sci.  nat.     (Cited  after  Braun  1879-93.) 
Brandes,  G. 

1892.    Zum  f  einer  Bau  der  Trematoden.    Zeit  f .  wiss.  Zool.,  53  :S58-577,  pi.  22. 
Braun,  M. 

1792.    Fortsetzung  der  Beytrage  zur  Kenntnis  der  Eingeweidewijrmer.     Sch. 
d.  Berlin  Ges.  nat.  Frde.,  10:57-65,  pi.  3.     (Cited  after  Braun  1879-93.) 
Braun,  M. 

1879-1893.    Vermes.  A.  Trematodes.    Bronn's  Klass.  u.  Ordnung.  d.  Thier- 

reichs,  B'd.  4,  Abt  I. 
1901.    Die  Trematoden  der  Chelonier.    Mitt.  Zool.  Mus.  Berlin,  2:13-20,  I  pi. 

191 1.  [Review  of  Stiles  and  Goldberger  1910.]  Zool.  Zent.,  18:705-707. 


86  ILLINOIS  BIOLOGICAL  MONOGRAPHS  [366 

BUBMEISTER,  R. 

1856.    Zoonomische  Briefe.    Allgemeine   Darstellung  der  thierischen   Organ- 
ization.    Leipzig,  pp.  250-252. 
Cekfontaine,  p. 

1896.    Contribution  a  I'etude  des  Octocotylides.    Arch.  Biol.,  14:497-552,  4  pi. 
1898.    Contribution    a    I'etude    des    Octocotylides.     Arch.    Biol.,    15:301-366, 
9  figs. 
DEU.E  Chiaje,  S. 

1823-1829.     Memorie  suUa  storia  e  notomia  degli  animali  senza  vertebre  del 
regno  di  Napoli-    4  vol.   Napoli.    (Cited  after  Stiles  and  Hassall  1902-1912.) 
COHN,  L. 

1903.  Zur    Kenntnis   einiger  Trematoden.     Cent  Bakt.  und  Par.,  34:35-42. 
4  figs. 

1904.  Helminthologische  Mitteilungen  II.    Arch.  f.  Naturg.,  pt.  i,  70:229:252. 
Creplin,  F.  C.  H. 

1844.  Endozoologische  Beitrage.     Arch.  f.  Naturg.,  10:112-133,  i  pi. 
Cunningham,  J.  T. 

1884.     A  New  Marine  Trematode  Belonging  to  the   Polystomidae.     Zool. 

Anz.,  7 :399. 
1887.    On  Stichocotyle  nephropis,  a  New  Trematode.    Trans.  Roy.  Soc  Edinb^ 

32:273-280,  I  pi. 
Daday,  E.  von 

1907.    In    sijdamerikanischen    Fischen    lebende    Trematoden-Arten.    Zool. 

Jahrb.,  Syst.,  24 :469-590,  6  pi. 
Delaroche,  F.  E. 

181 1.     Sur  deux  animaux  vivant  sur  les  branchies  des  poissons.     N.  Bull. 

Soc.  Philom.  Par.,  2:270-272,  pi.  2.     (Cited  after  Stiles  and  Hassall,  1902- 

1912.) 
DiESiNG,  K  M. 

1836.    Monographic    der    Gattungen    Amphistoma    und    Diplodiscus.      Ann. 

Wien.  Mus.  Naturg.,  i  :235-26o,  3  pi. 
1850.    Systema  Helminthum.     Vindobonne   1850.  vol.   i  :285-477. 
1859.     Nachtrage    und   Verbesserungen    zur    Revision     der     Myzhelminthen. 

Sitzg.  K.  Ak.  Wiss.  Wien,  math-nat.  CI,  35:421-454. 

DUJARDIN,  F. 

1845.  Histoire  naturelle  des  helminthes  ou  vers  intestinaux.     Paris. 

FiSCHOEDER,     F. 

1901.    Die  Paramphistomiden  der  Saugethiere.     Zool.   Anz.,  24:367-375. 
1903.    Die     Paramphistomiden     der     Saugethiere.       Zool.     Jahrb.,     Syst., 

17:485-660,   II  pi. 
Forbes,  S.  A. 

1896.    Cotylaspis  iiisigne.     Bien.  Rep.  St.  Lab.  Nat.  Hist.  Springfield,  111. 
Frohlich,  J.  A. 

1789.     Beschreibungen     einiger     neuer     Eingeweidewiirmer.     Naturforscher, 

Halle,  24:101-162,  figs.  1-31.     (Cited  after  Stiles  and  Hassall.  1902-1912.) 
1791.    B'eytrage  zur  Naturgeschichte  der  Eingeweidewiirmer.    Naturforscher, 

Halle,  25:52-113,  17  figs.     (Cited  after  Stiles  and  Hassall,  1902-1912.) 


367]  NORTH  AMERICAN  POLYSTOMIDAE—STUNKARD  87 

GOLDSCHMIDT,  R. 

1902.    Untersuchungen  uber  die  Eireifung,  Befruchtung  und  Zelltheilung  bei 

Polystomum  integerrimum  Rud.    Zeit.  f.  wiss.  Zool.,  71 :397-44S,  3  pi. 
\go2A.  B'emerkungen   zur  Entwicklungsgeschichte   des  Polystomum  integer- 
rimum Rud.    Zeit.  f.  wiss.  Zool.,  72:180-189,  11  figs. 
1909.    Eischale,  Schalendriise  und  Dotterzellen  der  Trematoden.    Zool.  Anz., 
34:481-498. 
Goto,  S. 

1894.    Studies  on  the  Ectoparasitic  Trematodes  of  Japan.    Jour.  Coll.  Sci., 

Imp.  Univ.  Japan,  8,  pt.  i,  300  pp.,  27  pi. 
1899.     Notes  on   Some  Exotic  Species  of  Ectoparasitic  Trematodes.     Jour. 
Coll.  Sci.,  Imp.  Univ.  Japan,  12:263-295,  2  pi. 
Halkin,  H. 

igo2.    Recherches  sur  la  maturation,  la  fecondation  et  la  developpement  du 
Polystomum  integerrimum.    Arch.  d.  Biol.,  18:291-359,  pi.  10-14. 
Haswell,  W.  a. 

1907.    Genito-intestinal  Canal  in  Polvclads.    Zool.  Anz.,  31 :643-644. 
HOYLE,  W.  E. 

1888.    Trematoda.    Encyc.  Brit.  9  ed.,  23 :53S-540. 

IjIMA,   I. 

1884.    Ueber  den  Zusammenhang  des  Eileiters  mit  dem  Verdauungscanal  bei 
gewissen  Polystomeen.     Zool.  Anz.,  7 :635-639. 
Jagerskiold,  L.  a. 

1899.    Ueber   den   Bau   von   Macraspis  elegans.    Of  vers.   Vet-Akad.   Fordh., 
3:197-214,  I  pi. 
Johnston,  S.  J. 

1912.     On  Some  Trematode  Parasites  of  Australian  Frogs.    Proc.  Linn.  Soc. 

N.  S.  Wales,  37:285-362,  pi.  14-43. 
1914.     Trematode  Parasites  and  the  Relationships  and  Distribution  of  their 
Hosts.    Rep.  Austral.  Ass.  Adv.  Sci.,  1914:272-278. 
Kelly,  H.  M. 

1899.    A  Statistical  Study  of  the  Parasites  of  the  Unionidae.    Bull.  111.  St 
Lab.  Nat.  Hist.,  5:399-418. 

KOFOID,    C.    A. 

1899.    On  the  Specific  Identity  of  Coiylaspis  insignis  Leidy  and  Platyaspis 
anadontae  Osborn.    Zool.  Bull.  Boston,  2:179-186. 
KuHL,  H.,  und  Hasselt,  J.  C.  van 

1822.    P oly stoma  midac.    Isis,  1822:113-115.     (Cited  after  Braun,  1879-1893.) 
KuHN,  J. 

1829.    Description  d'un  nouvel  epizoaire  du  genre  Polystomum  qui  se  trouve 
sur  les  branchies  de  la  petite  roussette  {Squalus  catulus)  suivie  de  quelques 
observations   sur  le  Distomum  megastomum  leporis.     Ann.   d.   sc.   d'obs., 
2 :46o-465. 
Leidy,  J. 

1851.    Helminthological    Contributions    II.      Proc.    Acad.    Nat.    Sci.    Phila., 
5 :224-227. 


88     .    NORTH  AMERICAN   PARAMPHISTOMIDAE—STUNKARD       [368 

1857.  Observations  on  Entozoa  Found  in  the  Naiades.     Proc.  Acad.  Nat. 
Sci.  Phila.,  9:18. 

1858.  Contributions    to    Helminthology.      Proc.     Acad.     Nat.     Sci.    Phila., 
10:110-112. 

1888.    Entozoa  of  the  Terrapin.    Proc.  Acad.  Nat.  Sci.  Phila.,  40:128. 
Linton,  E. 

1905.    Parasites  of  Fishes  of  Beaufort,  North  Carolina.     Bull.  Bur.  Fish., 
24:321-428,  34  pl- 
Looss,  A. 

1885.    Beitrage  zur  Kenntnis  der  Trematoden.    Zeit.  f.  wiss.  Zool.,  41 :390- 
446,  I  pl. 

1892.  Ueber    Ampkistomum    subclavatum    Rud.    und    seine    Entwicklung. 
Festschr.  Leuckart,  p.  147-168,  pl.  19-20. 

1893.  1st  der  Laurer's  Canal  der  Trematoden  eine  Vagina?    Centr.  f.  Bakt. 
u.  Par.,  13:808-819. 

1896.    Recherches   sur  la  Faune  parasitaire   de   I'figypt.     Premiere  partie, 

Mem.  de  ITnst.  egypt,  3:1-252,  16  pl. 
1899.    Weitere    Beitrage    zur    Kenntnis    der    Trematoden-Fauna   Aegyptens. 

Zool.  Jahrb.,  Syst,  12:521-784. 

1902.  Ueber   neue   und   bekannte   Trematoden    aus    Seeschildkroten.     Zool. 
Jahrb.,  Syst.,  16:411-594,  pl.  21-32. 

1912.  Ueber  den  Bau  einiger  auscheinend  seltener  Trematoden-Arten.  Zool. 
Jahrb.,  Suppl.,  15 :323-366,  3  pl. 

LuHE,  M. 

1909.    Parasitische    Plattwurmer.      i,    Trematodes.      Die    Siisswasserfanna 
I>eutschlands,  17:1-217,  188  figs. 
MacCallum,  G.  a. 

1913.  Fertilization  and  Egg-Laying  in  Microcotyle  stenotomi-    Science,  n.  s., 

37:340-341- 
MacCallum,  G.  A.,  and  MacCallum,  W.  G. 

1913.    On  Aspidogaster  ringens  and  A.  kemostoma  n.  sp.    Zool.  Jahrb.,  Syst., 
34:245-256,  4  figs. 
MacCallum,  W.  G. 

1905.    On   Two    New    Amphistome    Parasites    of    Sumatran   Fishes.     Zool. 
Jahrb.,  Syst.,  22:667-678,  2  figs. 
Mace,  E. 

1880.     Des  Trematodes  parasites  des  Grenouilles.     Bull.  Soc.  d'etud.   scien. 
Finistere,  Morlaix,  31  pp.,  4  pl.     (Cited  after  B'raun,  1879-1893.) 

MONTICELLI.  F.  S. 

1892.     Cotylogaster  michaelis  n.g.,  n.  sp.,  e  revisione  degli  Aspidobothridae. 
Festschr.  Leuckart,  p.  166-214,  2  pl. 

1903.  Per  una  nouva  classificatione  degli    "Heterocotylea".     Monit.    zool. 
Ital.,   14:334-337. 

NiCKERSON,  W.    S. 

1895.     On  Stichocotyle  nephropis  Cunningham,  a  Parasite  of  the  American 
Lobster.    Zool.  Jahrb.,  Anat.,  8:447-480,  3  pl. 


3»]  NORTH  AMERICAN  POLYSTOMIDAE—STUNKARD  89 

1902.    Cotologaster  occidentaUs  n.  sp.  and  a  Revision  of  the  Family  Aspido- 
bothridae.    Zool.  Johrb.,  Syst,  15 :597-624,  2  pi. 
Odhner,  T. 

1898.  Uber  die  geschlechtsreife  Form  von  Stichocotyle  nephropis  Cunning- 
ham.   Zool.  Anz.,  21 :509-5i3. 

191 1.  Zum  natiirlichen  System  der  digenen  Trematoden,  I.  Zool.  Anz.,  37: 
181-191. 

1911a.    Zum  naturlichen  System  der  digenen  Trematoden,  IV.    Zool.  Anz., 

38:513-531. 

1912.  Die  Homologien  der  weiblichen  Genitalwege  bei  den  Trematoden  und 
Cestoden.  Nebst  Bemerkungen  zum  naturlichen  System  der  monogenen 
Trematoden.    Zool.  Anz.,  39:337-351. 

1913.  Noch  einmal  die  Homologien  der  weiblichen  Genitalwege  der  mono- 
genen Trematoden.    Zool.  Anz.,  41  :S58-559. 

OSBORN,   H.   L. 

1898.  Observations  on  the  Anatomy  of  a  Species  of  Platyaspis  Found  Para- 
sitic on  the  Unionidae  of  Lake  Chautauqua.    Zool.  Bull.,  2  :S5-67,  6  figs. 

1904.    On  the  Habits  and  Structure  of  Cotylaspis  insignis  Leidy,  from  Lake 
Chautauqua,  N.  Y.    Zool.  Jahrb.,  Anat,  21 :20i-243,  3  pi. 
Otto,  H.  R. 

1896.  Beitrage  zur  Anatomie  und  Histologic  der  Amphistomiden.  Dtsch. 
Zeit.  Thiermed.,  22:85-141,  30  figs. 

POCHE,  F. 

1907.  Einige  Bemerkungen  zur  Nomenclature  der  Trematoden.  Zool.  Anz., 
31  :i24-i26. 

POIRIER,  J. 

1886.    Trematodes    nouveaux    ou    peu    connus.      Bull.    Soc.    Philom.    Paris, 

7  ser.,  10 :  20-40,  4  pi. 
Pratt,  H.  S. 

1900.     Synopses  of  North  American  Invertebrates,  XII.     The  Trematodes. 

Part  I.    The  Heterocotylea  or  Monogenetic  Forms.     Amer.  Nat.,  34:645- 

662,  50  figs- 

1908.  Parallel  Development  in  Trematodes.     Science,  n.  s.,  27:489. 
RUDOLPHI,  C.  A. 

1801.    B'ebachtungen  uber  die  Eingeweidewurmer.    Arch.  f.  Zool.  u.  Zootom., 

2:1-65. 
1809.    Entozoorum   sive  vermium   intestinalium   historia  naturalis.     Amste- 

laedami,  1809. 
1819.     Entozoorum  synopsis.    Berolini,  1819. 
St.  Remy,  G. 

1891.    Synopsis   des  Tremotodes   monogeneses       Rev.  Biol.   Nord.   France, 

4:1-92,  2  pi. 
1898.    Complement  du  synopsis  des  Trematodes  monogeneses.  Arch.  d.  Paras., 

1 :52i-S7i,  6  figs. 
Stafford,  J. 

1896.    Anatomical  structure  of  Aspidogaster  conchkola.    Zool.  Jahrb.,  Anat., 

9:477-542,  4  pl. 
1900.    Some  Undescribed  Trematodes.    Zool.  Jahrb.,  Syst,  13:399-414,  i  pl. 


90  NORTH   AMERICAN   POLYSTOMIDAE—STUNKARD  [370 

1905.    Trematodes  from  Canadian  Vertebrates.    Zool.  Anz.,  28:681-694. 
Stewart,  F.  H. 

1914.    The  Anatomy  of  Polystomum  kachugae  n.  sp.  with  Notes  on  the  Genus 
Polystomum.    Rec.  Ind.  Mus.,  10:195-205,  4  pi. 
Stieda,  L. 

1870.    Ueber  den  B'au  des  Polystomum  integerrimum.    Arch.  f.    Anat.  Phys. 
u.  Med.,  5:660-678,  I  pi. 
Stiles,  Ch.  W.,  and  Goldberger,  J. 

1910.    A  Study  o.f  the  Anatomy  of  Walsonius  walsoni  of  Man  and  of  Nine- 
teen Allied  Trematode  Worms  of  the  Superfamily  Paramphistomoidea- 
Bull.  Hyg.  Lab.,  No.  60:1-264,  205  figs. 
Stiles,  Ch.  W.,  and  Hassall,  A. 

1902-1912.    Index-Catalogue  of  Medical  and  Veterinary  Zoology.    Bull.  Bur. 

Animal  Ind.,  No.  39. 
1908.    Index-Catalogue  of  Medical  and  Veterinary  Zoology.    Bull.  Hyg.  Lab., 
No.  37:89. 
Stunkard,  H.  W. 

1916.    On  the  Anatomy  and  Relationships  of  Some  North  American  Trema- 
todes.   Jour.  Par.,  3 :2i-27. 
Taschenberg,  O.  E. 

1879.    Zur    Systematik   der   Monogenetischen   Tematoden.     Zeit.    gesammfc 
Naturwissensch.,    52 1232-265. 
Treutler,  F.  a. 

I793-    Observationes  pathologico-anatomicae,  auctariam  ad   helminthologiam 
humani  corporis  continentes.    Diss,  in  praes.    Ch.  F.  Ludwig.  Lips.    (Cited 
after  Braun,  1879-1893.) 
Voeltzkow,  a. 

1888.    Aspidogaster  conchicola.    Arb.  zool.-zootom.  Inst.  Wurzb.,  8:249-29^ 

.5   pl. 
Walter,  E. 

1893.    Untersuchungen  fiber  den  Ban  der  Trematoden.    Zeit.  f.  wiss.  Zool., 
56:189-243,  3  pl. 

WILLEMOES-SUHM,  R.  VON 

1872.    Zur  Naturgeschichte  des  Polystomum  integerrimum  and  Polystomum 
ocellatum.    Zeit.  f.  wiss.  Zool.,  22:29-39,  i  pl. 
Wright,   R.    R. 

1879.    Contributions  to  American  Helminthology.    Jour.  Proc  Canad.  Inst, 
N.  S.,  I  :i-23,  2  pl. 
Wright,  R.  R.,  and  Macallum,  A.  B. 

1887.    Sphyranura  osleri.    Jour.  Morph.,  I  :i-48,  i  pl. 
Zeder,  J.  G.  H. 

1800.    Erster   Nachtrag  zur   Naturgeschichte    der    Eingeweidew firmer  von 
J.  A.  G.  Goeze.    Leipzig,  1800. 
Zeller,  E. 

1872.    Untersuchungen  fiber  die  Entwicklung  und  Bau  des  Polystomum  iu- 

tegerrimum  Rud.    Zeit  f.  wiss.  Zool.,  22:1-28,  2  pl. 
1876.    Weiterer  Beitrag  zur  Kenntniss  der  Polystomen.    Zeit  f.  wiss.  Zool., 
27:238-275,  2  pl. 


371] 


NORTH  AMERICAN  POLYSTOMIDAE—STUNKARD 


91 


EXPLANATION   OF   PLATES 

All  figures  except  those  of  reconstruction  were  drawn  with  the  aid  of  a 
camera  lucida  and  were  made  from  permanent  mounts. 

Abbreviations  used 


a 

acetabulum 

nc 

nerve  commissure 

b 

esophageal  bulb 

0 

ovary 

cm 

circular  muscles 

oc 

eye  spot 

cs 

cirrus  sac 

od 

oviduct 

e 

esophagus 

om 

oblique  muscles 

ed 

excretory  duct 

00 

ootype 

ep 

excretory  pore 

op 

oral  evagination 

gp 

genital  pore 

OS 

oral  sucker 

gc 

genito-intestinal  canal 

ov 

egg 

h 

small  booklets 

p 

postate  gland 

hd 

hermaphroditic  duct 

Ph 

pharynx 

i 

intestine 

sp 

septum 

I 

Laurer's  canal 

sv 

seminal  vesicle 

Im 

longitudinal  muscles 

t 

testis 

Is 

lymph  sinus 

u 

uterus 

It 

limiting  membrane 

ud 

uterine  duct 

m 

mouth 

V 

vitellaria 

md 

median  dorsal  lymph  canal 

vd 

vas  deferens 

mg 

Mehlis'  gland 

vg 

vagina 

mo 

marginal  organ 

vl 

vitelline  duct 

mt 

metraterm 

w 

vitello-vaginal  canal 

mv 

median  ventral  lymph  canal 

373]  NORTH  AMERICAN  POLYSTOMIDAE—STUNKARD  93 


PLATE  I 


94  ILLINOIS  BIOLOGICAL  MONOGRAPHS  1374 


EXPLANATION  OF  PLATE 

POLYSTOMA  ORBICULARE 

Fig.  I.  Entire  specimen,  extended,  ventral  view.    X  35- 

Fig.  2.  Hook  from  genital  coronet    X  225. 

Fig.  3.  Reconstruction  of  genital  apparatus  from  frontal  sections.    X  I35- 

Fig.  4.  Sagittal  section  thru  caudal  disc.    X  87. 

Fig.  5.  Frontal  section  thru  caudal  disc.    X  VZ- 

Fig.  6.  Sagittal  section  thru  oral  sucker  and  pharynx.    X  140. 


ILLINOIS   BIOLOGICAL  MONOGRAPHS 


VOLUME  3 


ttd- f 


STUNKARD 


NORTH  AMERICAN  POLYSTOMIDAE 


PLATE  I 


375]  NORTH  AMERICAN  POLYSTOMIDAE—STUNKARD  95 


PLATE  II 


96  ILLIXOIS  BIOLOGICAL  MONOGRAPHS  [376 


EXPLANATION  OF  PLATE 

POLYSTOMA    ORBICULARE 

Fig.    7-    Frontal  section.     X  35- 

Fig.    8.    Frontal  section  of  ootype  and  beginning  of  uterine  duct.     X  i8s. 

Fig.    9.     Frontal   section   of    ootype   and   end   of   right  vitello-vaginal  canal,   five 

sections  ventral  to  Figure  8.     X  185. 
Fig.  10.    Frontal   section,   o6type   region  of   same   specimen  as  Figures  8  and  9, 
showing  ovary,  uterus,  oviduct,  uterine  duct,  genito-intestinal  canat 
and   vas   deferens.     X  140. 
Frontal    section    showing   vitellaria    and    origin    of    vitelline    ducts    with 

granular  secretion  in  the  cells  and  duct.     X  87. 
Frontal  section  thru  cirrus  sac  at  the  juncture  of  the  shanks  and  roots  of 
the  genital  hooks,  showing  the  genital  papillae  cut  across,  and  a  sec- 
tion of  the  duct  from  the  uterus  at  the  bottom  of  the  figure.    X  250. 
Reconstruction  of  male  genital  apparatus  from  sagittal  sections.    X  140. 
Frontal   section  thru  uterus  showing  embryo  in  stage  of   a  morula-like 
mass  of  cells.     X  700. 


Fig. 

II. 

Fig. 

12. 

Fig. 

Fig. 

13- 

14- 

ILLINOIS  BIOLOGICAL  MONOGRAPHS 

8 


VOLUME  3 


VV  00 

STUXKARD  XORTH  AMERICAX  POLYSTOMIDAE  PLATE  II 


377]  NORTH  AMERICAN  POLYSTOMIDAE—STUNKARD  97 


PLATE  III 


98  ILLIXOIS  BIOLOGICAL  MONOGRAPHS  [378 


EXPLANATION  OF  PLATE 

POLYSTOMA   OPACUM 

Fig.  15.     Entire  specimen,  extended,  ventral  view.     X  20. 

Fig.  16.     Reconstruction    of    genital    apparatus    from    toto    preparation    and   cross 

sections.     X  50. 
Fig.  I".     Hook  from  genital  coronet.    X  SSO. 
Fig.  18.    Frontal  section  thru  the  anterior  sucker  and  pharynx,  showing  in  section 

nerve  commissures  and  vitellaria.     X  60. 
Fig.  19.    Cross  section  of  body  thru  uterus  and  cirrus  sac.     X  60. 
Fig.  20.    Cross  section  of  body  thru  the  testis.     X  60. 
Fig.  21.     Cross  section  thru  the  anterior  pair  of  bothria.     X  60.  ' 


ILLINOIS   BIOLOGICAL   MONOGRAPHS 

16 


VOLUME  3 


STUNKARD  NORTH  AMERICAN  POLYSTOMIDAE 


PLATE  III 


379]  NORTH  AMERICAN  POLYSTOMIDAE—STUNKARD  99 


PLATE  IV 


100  ILLINOIS  BIOLOGICAL  MONOGRAPHS  [380 


EXPLANATION  OF  PLATE 

POLYSTOMA    MEGACOTYLE 

Fig.  22.  Entire  specimen,  ventral  view.     X  27. 

Fig.  23.  Cross  section  of  body  thru  ovary  and  uterus.    X  60. 

Fig.  24.  Cross  section  of  body  thru  vaginae  and  anterior  part  of  the  testis.   X  60. 

Fig.  25.  Cross  section  thru  the  pharynx  near  the  posterior  end.     X  85. 

Fig.  26.  Cross  section  of  seminal  vesicle  and  cirrus  sac.     X  140. 

POLYSTOMA     CORONATUM 

Fig.  27.    Entire  specimen,  ventral  view.     X  27. 


lUJXOIS   BIOLOGICAL   MOXOGRAPHS 

23 


VOLUME  3 


0_?   O  OO  C*^ 


STUNKARD 


NORTH  AMERICAN  POLYSTOMIDAE 


PLATE  IV 


381]  NORTH  AMERICAN  POLYSTOMIDAE—STUNKARD  101 


PLATE  V 


tt2  ILLINOIS  BIOLOGICAL  MONOGRAPHS  [382 


EXPLANATIOX  OF  PLATE 

POLYSTOMA     MICROCOTYLE 

Fig.  28.    Entire  specimen,  ventral  view.     X  27. 

Fig.  29.  Ventral  view  of  caudal  disc,  showing  arrangement  of  musculature  and 
hooks.     X43- 

POLVSTOM.\    HASSALLI 

Fig.  30.    Entire  specimen,  ventral  view,  ceca  connected  posteriorly.     X  45. 

Fig.  31.  Entire  specimen,  ventral  view,  in  which  there  is  no  posterior  connexion 
between  the   ceca.     X  40. 

Fig.  32.     Reconstruction  of  genital  apparatus  from  frontal  sections.    X  135. 

Fig-  2Z-  Frontal  section  thru  the  dorsal  part  of  the  uterus,  showing  oral  sucker, 
pharynx,  nerve  commissures,  intestine,  excretory  vesicles  and  ducts, 
vitellaria  and  smaller  tubes  of  the  ootype  region.     X  60. 


ILLIXOIS   BIOLOGICAL   MOXOGRAPHS 


VOLUME   3 


STUXKARD 


NORTH  AMERICAN  POLYSTOMIDAE 


PLATE  V 


383]  NORTH  AMERICAN  POLYSTOMIDAE—STUNKARD  103 


PLATE  VI 


104 


ILLINOIS  BIOLOGICAL  MONOGRAPHS 


1384 


EXPLAXATIOX  OF  PLATE 


Fig. 

34. 

Fig. 

35- 

Fig. 

36. 

Fig. 

37. 

Fig. 

38. 

F-ig. 

39. 

Fig. 

40. 

Fig. 

41. 

Fig. 

42. 

Fig. 

43. 

Fig. 

44. 

Fig.  45. 


Suckers  .^xd  Hooks  of  V.^8I0l•s  Species  of  Polystomes 
Polystotr.a  orbiculare,  bothriuin  from  caudal  disc.     X  140- 
Polystoiiia  orbiculare.  frontal   section   thru  bothrium.     X  140. 
Polystoitia  obiculare,    optical    section     of     bothriuin     showing     cuticular 

framework.     X  140. 
'  Poly  stoma  opacum,  hook    from   base   of    sucker.     X  165. 
Polystoma  ofiacuin,  hook  from  anterior  margin  of  caudal  disc.     X  165. 
Polystoina  microcotyle,  hooks  of  posterior  margin  of  disc.     X  165. 
Polystoma  opacum,   hooks   of  posterior  margin  of  disc.      X  165. 
Polystoma  megacotylc,   hooks   of   posterior   margin    of   disc.      X  165. 
Polystoma  coroiiatuiii,   hooks   of   posterior    margin    of    disc.      X  165. 
Polystoma  orbiculare,  hook  from  base  of  sucker.     X  165. 
Polystoma  orbiculare,  frontal  section  thru  a  sucker  illustrating  the  method 

of   operation ;   the  external  zones  are   retracted   with   the  resulting 

protrusion  of  the  basal  part.     X  140. 
Polystoma  iittcgerrimum,  frontal  section  thru  a  sucker  showing  type  of 

cuticular   framework.     Compare  with   text  and   types   illustrated  in 

other  figures.     X  100. 


lELIXOIS   BIOLOGICAL  MOXOGRAPHS 

34  ^^ 


VOLUME  3 


STUXKARD  XORTH  AMERICAN  POLYSTOMIDAE 


PLATE  VI 


38S]  NORTH  AMERICAN  ASPIDOGASTRIDAE—STUNKARD  105 


PLATE  VII 


106  ILLINOIS  BIOLOGICAL  MONOGRAPHS  [386 


EXPLANATION  OF  PLATE 

COTYLASPIS  COKERI 

Fig.  46.    Entire  specimen,  extended,  dorsal  view.     X  40. 

Fig.  47.    Ventral   view   of  entire  specimen   showing  position  of   marginal  organs 

and  divisions  of  the  adhesive  disc.     X  40. 
Fig.  48.    Reconstruction   of    reproductive   organs    from   frontal   sections.     X  80. 
Fig.  49.    .Cross  section  of  body  at  the  level  of  the  ovary  showing  the  ovary,  uterus, 

seminal    vesicle,    intestine,    excretory    ducts,   and   a    follicle    of    the 

vitellaria.     X  87. 
Fig.  50.    Diagrammatic    representation    of    the    excretory    system    from    a    living 

specimen,  dorsal  view.     X  40. 
Fig.  51.     Oblique  section  of  body  just  posterior  to  the  genital  pores,  showing  in 

section  the  mouth   funnel,  pharynx,  cirrus  sac,  uterus,  septum  ,ind 

adhesive  disc.     X  87. 
Fig.  52.     Entire  specimen,  contracted,  dorsal  view.     X  40. 


ILLl.XOIS   BIOLOGICAL   MOXOGRAPHS 
46 


VOLUME  3 


STUXKARD        NORTH  AMERICAN'  ASPIDOGASTRIDAE  PLATE  VII 


■IV. 


V'  ■ 


387]  NORTH  AMERICAN  ASPIDOGASTRIDAE—STUNKARD  107 


PLATE  VIII 


108  ILLIXOIS  BIOLOGICAL  MONOGRAPHS  [388 


EXPLANATION  OF  PLATE 

COTYLASPIS  COKERI    (EXCEPT  FiGURE  S6) 

Fig.  $3.  Sagittal  section  thru  the  anterior  end  of  body  showing  musculature,  di- 
gestive and  reproductive  organs.     X  200. 

Fig.  54.    Frontal  section  thru  the  openings  of  the  genital  pores.     X  85. 

Fig.  55.  Section  thru  a  marginal  organ ;  a  muscle  fiber  is  seen  at  the  left  of  the 
figure  and  on  the  other  side  a  nerve  fibril  passes  to  the  inner  end  of 
the  thick  walled  part  of  the  canal.  In  this  section  the  canal  is  cut 
across  and  can  not  be  traced  from  the  bulb  to  the  exterior.     X  580. 

Fig.  56.    Section  thru  a  marginal  organ  in  Cotylaspis  insignis.    X  580. 

Fig.  57.  Frontal  section  thru  the  adhesive  disc  showing  arrangement  of  muscula- 
ture.    X  95- 

Fig.  58.  Section  thru  the  anterior  part  of  the  forebody  showing  the  base  of  the 
mouth  funnel,  anterior  part  of  the  pharynx,  nerve  commissure  and 
eye  spots.    X  800. 


ILLIXOIS  BIOLOGICAL   MOXOGRAPHS 
53 


VOLUME   3 


STUXKARD        XORTH  AMERICAX  ASPIDOGASTRIPAE         PLATE  \III 


389]        NORTH  AMERICAN  PARAMPHISTOMIDAE—STUNKARD         109 


PLATE  IX 


110  ILLINOIS  BIOLOGICAL  MONOGRAPHS  [390 


EXPLANATION  OF  PLATE 

Alassostoma  magnum 
Fig.  59.    Entire  specimen,  ventral  view.     X  9. 
Fig.  60.    Cross   section  thru  the  genital   pore  showing  the  terminal  parts  of  the 

cirrus  sac  and  uterus,  the  hemaphroditic  duct,   genital   sinus,   four 

layers  of  muscles  in  the  body  wall  and  the  muscle  lamellae  of  the 

esophageal  bulb.     X27. 
Fig.  61.    Diagrammatic  representation  of   female  genital   apparatus   reconstructed 

from  cross  sections.     X40. 
Fig.  62.     Section  of  the  wall  of  the  intestine.     X360. 

Fig.  63.    Cross  section  thru  the  oral  sucker  and  the  oral  evaginations.     X  40. 
Fig.  64.    Cross  section  of  body  at  the  level  of  the  ovary  showing  in  section  the 

ovary,  uterus,  Laurer's  canal,  the  ceca,  vitellaria,  lymph  spaces  and 

excretory  ducts.     X 16. 
Fig.  65.    Cross  section  thru  the  oral  sucker  showing  arrangement  of  muscle  fibers 

and  position  of  the  nuclear  zone.     X  35. 


ILLINOIS   BIOLOGICAL   MONOGRAPHS 


VOLUME  3 


STUNKARD 


NORTH  AMERICAN  PARAMPHISTOMIDAE 


PLATE  IX 


391]        NORTH  AMERICAN  PARAMPHISTOMIDAE—STUNKARD         111 


PLATE  X 


112  ILLIXOIS  BIOLOGICAL  MOSOGRAPHS  [392 


EXPLANATION  OF  PLATE 

Alassostoma  parvum 
Fig.  66.    Entire  specimen,  ventral  view.     X  27. 
Fig.  67.    Cross    section    of    body    posterior   to   the    ovary    showing   coils    of    the 

excretory   ducts.     X  70. 
Fig.  68.    Cross  section  thru  the  posterior  part  of  the  acetabulum  showing  lymph 

spaces  around  the  sucker.     X  "o. 
Fig.  69.    Cross  section  a  short  distance  posterior  to  the  genital  pore  showing  in 

section,  the  uterus,  the  cirrus  sac,  and  above  the  latter  organ  three 

loops  of  the  seminal  vesicle.     X  70. 
Fig.  70.    Cross  section  of  esophageal  bulb  with  clusters  of  surrounding  cells.  X  "o. 
Fig.  71.    Cross  section  of  body  thru  the  genital  pore  showing  hermaphroditic  duct, 

cirrus  sac,  lymph  spaces  and  the  character  of  the  parenchyma.     X  90. 


ILLISOIS  BIOLOGICAL  MONOGRAPHS 
66         .^'"^  67 


VOLUME  3 


STUNKARD        NORTH  AMERICAN'  PARAMPHISTOMIDAE         PLATE  X 


J93]        NORTH  AMERICAN  PARAMPHISTOMIDAE—STUNKARD         113 


PLATE  XI 


114  ILLISOIS  BIOLOGICAL  MOXOGRAPHS  [39+ 


Fig. 
Fig. 

72. 
72- 

Fig. 
Fig. 

74- 
75- 

Fig. 

76. 

Fig. 

77- 

Fig. 

78. 

Fig. 

79- 

EXPLANATION  OF  PLATE 

Zygocotyle  ceratosa 
Entire   specimen,   ventral   view.    X  u. 
Cross  section  of  esophageal  bulb,  showing  the  arrangement  of  the  muscle 

fibers.     X  45-     Compare  with  Figures  60  and  70. 
Cross  section  of  bodj'  thru  the  origin  of  the  oral  evaginations.     X  45. 
Sagittal  section  thru  the  anterior  part  of  the  body  showing  oral  sucker, 

an  oral  evagination  and  the  anterior  part  of  the  esophagus.     X  45. 
Sagittal  section  of  posterior  part  of  body  thru  one  side  of  the  acetabulum. 

X27. 
Sagittal  section  of  the  posterior  part  of  the  body  near  the  median  line, 

showing  the  ovary,  eggs  in  the  uterus,  Laurer's  canal,  and  the  shape 

of   the   acetabulum.     X  27. 
Sagittal  section  thru  the  body  one  section  at  the  side  of  the  genital  pores 

showing  the   folded  wall   of   the   uterus   and   the   ejaculatory   duct 

which  in  this  species  is  without  a  cirrus  sac.     X  136. 
Representation  of  the  sagittal  section  thru  the  openings  of  Laurer's  canal 

and  the  excretory  vesicle.     X  90. 


ILLIXOIS  BIOLOGICAL   MONOGRAPHS 


STUXKARD  NORTH  AMERICAN  PARAMPHISTOMIDAE  PLATE  XI 


UNIVERSITY  OF  ILLINOIS-URBANA 

S7D.5ILL  CDI14 

ILLINOIS  BIOLOGICAL  MONOGRAPHS  URBANA 

31918-17 


01 


01 


7753408 


